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* mm/mlock.c: change count_mm_mlocked_page_nr return typeswkhack2019-06-131-2/+2
| | | | | | | | | | | | | | | On a 64-bit machine the value of "vma->vm_end - vma->vm_start" may be negative when using 32 bit ints and the "count >> PAGE_SHIFT"'s result will be wrong. So change the local variable and return value to unsigned long to fix the problem. Link: http://lkml.kernel.org/r/20190513023701.83056-1-swkhack@gmail.com Fixes: 0cf2f6f6dc60 ("mm: mlock: check against vma for actual mlock() size") Signed-off-by: swkhack <swkhack@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock.c: mlockall error for flag MCL_ONFAULTPotyra, Stefan2019-06-131-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | If mlockall() is called with only MCL_ONFAULT as flag, it removes any previously applied lockings and does nothing else. This behavior is counter-intuitive and doesn't match the Linux man page. For mlockall(): EINVAL Unknown flags were specified or MCL_ONFAULT was specified without either MCL_FUTURE or MCL_CURRENT. Consequently, return the error EINVAL, if only MCL_ONFAULT is passed. That way, applications will at least detect that they are calling mlockall() incorrectly. Link: http://lkml.kernel.org/r/20190527075333.GA6339@er01809n.ebgroup.elektrobit.com Fixes: b0f205c2a308 ("mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage") Signed-off-by: Stefan Potyra <Stefan.Potyra@elektrobit.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove zone_lru_lock() function, access ->lru_lock directlyAndrey Ryabinin2019-03-051-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | We have common pattern to access lru_lock from a page pointer: zone_lru_lock(page_zone(page)) Which is silly, because it unfolds to this: &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock while we can simply do &NODE_DATA(page_to_nid(page))->lru_lock Remove zone_lru_lock() function, since it's only complicate things. Use 'page_pgdat(page)->lru_lock' pattern instead. [aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()] Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dax: remove VM_MIXEDMAP for fsdax and device daxDave Jiang2018-08-171-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch is reworked from an earlier patch that Dan has posted: https://patchwork.kernel.org/patch/10131727/ VM_MIXEDMAP is used by dax to direct mm paths like vm_normal_page() that the memory page it is dealing with is not typical memory from the linear map. The get_user_pages_fast() path, since it does not resolve the vma, is already using {pte,pmd}_devmap() as a stand-in for VM_MIXEDMAP, so we use that as a VM_MIXEDMAP replacement in some locations. In the cases where there is no pte to consult we fallback to using vma_is_dax() to detect the VM_MIXEDMAP special case. Now that we have explicit driver pfn_t-flag opt-in/opt-out for get_user_pages() support for DAX we can stop setting VM_MIXEDMAP. This also means we no longer need to worry about safely manipulating vm_flags in a future where we support dynamically changing the dax mode of a file. DAX should also now be supported with madvise_behavior(), vma_merge(), and copy_page_range(). This patch has been tested against ndctl unit test. It has also been tested against xfstests commit: 625515d using fake pmem created by memmap and no additional issues have been observed. Link: http://lkml.kernel.org/r/152847720311.55924.16999195879201817653.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Dave Jiang <dave.jiang@intel.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, mlock, vmscan: no more skipping pagevecsShakeel Butt2018-02-211-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a thread mlocks an address space backed either by file pages which are currently not present in memory or swapped out anon pages (not in swapcache), a new page is allocated and added to the local pagevec (lru_add_pvec), I/O is triggered and the thread then sleeps on the page. On I/O completion, the thread can wake on a different CPU, the mlock syscall will then sets the PageMlocked() bit of the page but will not be able to put that page in unevictable LRU as the page is on the pagevec of a different CPU. Even on drain, that page will go to evictable LRU because the PageMlocked() bit is not checked on pagevec drain. The page will eventually go to right LRU on reclaim but the LRU stats will remain skewed for a long time. This patch puts all the pages, even unevictable, to the pagevecs and on the drain, the pages will be added on their LRUs correctly by checking their evictability. This resolves the mlocked pages on pagevec of other CPUs issue because when those pagevecs will be drained, the mlocked file pages will go to unevictable LRU. Also this makes the race with munlock easier to resolve because the pagevec drains happen in LRU lock. However there is still one place which makes a page evictable and does PageLRU check on that page without LRU lock and needs special attention. TestClearPageMlocked() and isolate_lru_page() in clear_page_mlock(). #0: __pagevec_lru_add_fn #1: clear_page_mlock SetPageLRU() if (!TestClearPageMlocked()) return smp_mb() // <--required // inside does PageLRU if (!PageMlocked()) if (isolate_lru_page()) move to evictable LRU putback_lru_page() else move to unevictable LRU In '#1', TestClearPageMlocked() provides full memory barrier semantics and thus the PageLRU check (inside isolate_lru_page) can not be reordered before it. In '#0', without explicit memory barrier, the PageMlocked() check can be reordered before SetPageLRU(). If that happens, '#0' can put a page in unevictable LRU and '#1' might have just cleared the Mlocked bit of that page but fails to isolate as PageLRU fails as '#0' still hasn't set PageLRU bit of that page. That page will be stranded on the unevictable LRU. There is one (good) side effect though. Without this patch, the pages allocated for System V shared memory segment are added to evictable LRUs even after shmctl(SHM_LOCK) on that segment. This patch will correctly put such pages to unevictable LRU. Link: http://lkml.kernel.org/r/20171121211241.18877-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shaohua Li <shli@fb.com> Cc: Jan Kara <jack@suse.cz> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: docs: fixup punctuationMike Rapoport2018-02-061-1/+1
| | | | | | | | | | | so that kernel-doc will properly recognize the parameter and function descriptions. Link: http://lkml.kernel.org/r/1516700871-22279-2-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Eliminate cond_resched_rcu_qs() in favor of cond_resched()Paul E. McKenney2017-11-281-1/+1
| | | | | | | | | | | Now that cond_resched() also provides RCU quiescent states when needed, it can be used in place of cond_resched_rcu_qs(). This commit therefore makes this change. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz>
* mm: mlock: remove lru_add_drain_all()Shakeel Butt2017-11-151-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | lru_add_drain_all() is not required by mlock() and it will drain everything that has been cached at the time mlock is called. And that is not really related to the memory which will be faulted in (and cached) and mlocked by the syscall itself. If anything lru_add_drain_all() should be called _after_ pages have been mlocked and faulted in but even that is not strictly needed because those pages would get to the appropriate LRUs lazily during the reclaim path. Moreover follow_page_pte (gup) will drain the local pcp LRU cache. On larger machines the overhead of lru_add_drain_all() in mlock() can be significant when mlocking data already in memory. We have observed high latency in mlock() due to lru_add_drain_all() when the users were mlocking in memory tmpfs files. [mhocko@suse.com: changelog fix] Link: http://lkml.kernel.org/r/20171019222507.2894-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Balbir Singh <bsingharora@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, pagevec: remove cold parameter for pagevecsMel Gorman2017-11-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | Every pagevec_init user claims the pages being released are hot even in cases where it is unlikely the pages are hot. As no one cares about the hotness of pages being released to the allocator, just ditch the parameter. No performance impact is expected as the overhead is marginal. The parameter is removed simply because it is a bit stupid to have a useless parameter copied everywhere. Link: http://lkml.kernel.org/r/20171018075952.10627-6-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm/mlock.c: use page_zone() instead of page_zone_id()Joonsoo Kim2017-09-081-6/+4
| | | | | | | | | | | | | | | | page_zone_id() is a specialized function to compare the zone for the pages that are within the section range. If the section of the pages are different, page_zone_id() can be different even if their zone is the same. This wrong usage doesn't cause any actual problem since __munlock_pagevec_fill() would be called again with failed index. However, it's better to use more appropriate function here. Link: http://lkml.kernel.org/r/1503559211-10259-1-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mlock: fix mlock count can not decrease in race conditionYisheng Xie2017-06-021-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Kefeng reported that when running the follow test, the mlock count in meminfo will increase permanently: [1] testcase linux:~ # cat test_mlockal grep Mlocked /proc/meminfo for j in `seq 0 10` do for i in `seq 4 15` do ./p_mlockall >> log & done sleep 0.2 done # wait some time to let mlock counter decrease and 5s may not enough sleep 5 grep Mlocked /proc/meminfo linux:~ # cat p_mlockall.c #include <sys/mman.h> #include <stdlib.h> #include <stdio.h> #define SPACE_LEN 4096 int main(int argc, char ** argv) { int ret; void *adr = malloc(SPACE_LEN); if (!adr) return -1; ret = mlockall(MCL_CURRENT | MCL_FUTURE); printf("mlcokall ret = %d\n", ret); ret = munlockall(); printf("munlcokall ret = %d\n", ret); free(adr); return 0; } In __munlock_pagevec() we should decrement NR_MLOCK for each page where we clear the PageMlocked flag. Commit 1ebb7cc6a583 ("mm: munlock: batch NR_MLOCK zone state updates") has introduced a bug where we don't decrement NR_MLOCK for pages where we clear the flag, but fail to isolate them from the lru list (e.g. when the pages are on some other cpu's percpu pagevec). Since PageMlocked stays cleared, the NR_MLOCK accounting gets permanently disrupted by this. Fix it by counting the number of page whose PageMlock flag is cleared. Fixes: 1ebb7cc6a583 (" mm: munlock: batch NR_MLOCK zone state updates") Link: http://lkml.kernel.org/r/1495678405-54569-1-git-send-email-xieyisheng1@huawei.com Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com> Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Joern Engel <joern@logfs.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: zhongjiang <zhongjiang@huawei.com> Cc: Hanjun Guo <guohanjun@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make try_to_munlock() return voidMinchan Kim2017-05-031-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped the page has VM_LOCKED flag. In that time, VM set PG_mlocked to the page if the page is not pte-mapped THP which cannot be mlocked, either. With that, __munlock_isolated_page can use PageMlocked to check whether try_to_munlock is successful or not without relying on try_to_munlock's retval. It helps to make try_to_unmap/try_to_unmap_one simple with upcoming patches. [minchan@kernel.org: remove PG_Mlocked VM_BUG_ON check] Link: http://lkml.kernel.org/r/20170411025615.GA6545@bbox Link: http://lkml.kernel.org/r/1489555493-14659-5-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'prep-for-5level'Linus Torvalds2017-03-101-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge 5-level page table prep from Kirill Shutemov: "Here's relatively low-risk part of 5-level paging patchset. Merging it now will make x86 5-level paging enabling in v4.12 easier. The first patch is actually x86-specific: detect 5-level paging support. It boils down to single define. The rest of patchset converts Linux MMU abstraction from 4- to 5-level paging. Enabling of new abstraction in most cases requires adding single line of code in arch-specific code. The rest is taken care by asm-generic/. Changes to mm/ code are mostly mechanical: add support for new page table level -- p4d_t -- where we deal with pud_t now. v2: - fix build on microblaze (Michal); - comment for __ARCH_HAS_5LEVEL_HACK in kasan_populate_zero_shadow(); - acks from Michal" * emailed patches from Kirill A Shutemov <kirill.shutemov@linux.intel.com>: mm: introduce __p4d_alloc() mm: convert generic code to 5-level paging asm-generic: introduce <asm-generic/pgtable-nop4d.h> arch, mm: convert all architectures to use 5level-fixup.h asm-generic: introduce __ARCH_USE_5LEVEL_HACK asm-generic: introduce 5level-fixup.h x86/cpufeature: Add 5-level paging detection
| * mm: convert generic code to 5-level pagingKirill A. Shutemov2017-03-091-0/+1
| | | | | | | | | | | | | | | | | | | | | | Convert all non-architecture-specific code to 5-level paging. It's mostly mechanical adding handling one more page table level in places where we deal with pud_t. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | thp: fix another corner case of munlock() vs. THPsKirill A. Shutemov2017-03-091-5/+4
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following test case triggers BUG() in munlock_vma_pages_range(): int main(int argc, char *argv[]) { int fd; system("mount -t tmpfs -o huge=always none /mnt"); fd = open("/mnt/test", O_CREAT | O_RDWR); ftruncate(fd, 4UL << 20); mmap(NULL, 4UL << 20, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED | MAP_LOCKED, fd, 0); mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_LOCKED, fd, 0); munlockall(); return 0; } The second mmap() create PTE-mapping of the first huge page in file. It makes kernel munlock the page as we never keep PTE-mapped page mlocked. On munlockall() when we handle vma created by the first mmap(), munlock_vma_page() returns page_mask == 0, as the page is not mlocked anymore. On next iteration follow_page_mask() return tail page, but page_mask is HPAGE_NR_PAGES - 1. It makes us skip to the first tail page of the next huge page and step on VM_BUG_ON_PAGE(PageMlocked(page)). The fix is not use the page_mask from follow_page_mask() at all. It has no use for us. Link: http://lkml.kernel.org/r/20170302150252.34120-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/user.h> We are going to split <linux/sched/user.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/user.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* thp: fix corner case of munlock() of PTE-mapped THPsKirill A. Shutemov2016-11-301-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following program triggers BUG() in munlock_vma_pages_range(): // autogenerated by syzkaller (http://github.com/google/syzkaller) #include <sys/mman.h> int main() { mmap((void*)0x20105000ul, 0xc00000ul, 0x2ul, 0x2172ul, -1, 0); mremap((void*)0x201fd000ul, 0x4000ul, 0xc00000ul, 0x3ul, 0x203f0000ul); return 0; } The test-case constructs the situation when munlock_vma_pages_range() finds PTE-mapped THP-head in the middle of page table and, by mistake, skips HPAGE_PMD_NR pages after that. As result, on the next iteration it hits the middle of PMD-mapped THP and gets upset seeing mlocked tail page. The solution is only skip HPAGE_PMD_NR pages if the THP was mlocked during munlock_vma_page(). It would guarantee that the page is PMD-mapped as we never mlock PTE-mapeed THPs. Fixes: e90309c9f772 ("thp: allow mlocked THP again") Link: http://lkml.kernel.org/r/20161115132703.7s7rrgmwttegcdh4@black.fi.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mlock: avoid increase mm->locked_vm on mlock() when already ↵Simon Guo2016-10-071-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mlock2(,MLOCK_ONFAULT) When one vma was with flag VM_LOCKED|VM_LOCKONFAULT (by invoking mlock2(,MLOCK_ONFAULT)), it can again be populated with mlock() with VM_LOCKED flag only. There is a hole in mlock_fixup() which increase mm->locked_vm twice even the two operations are on the same vma and both with VM_LOCKED flags. The issue can be reproduced by following code: mlock2(p, 1024 * 64, MLOCK_ONFAULT); //VM_LOCKED|VM_LOCKONFAULT mlock(p, 1024 * 64); //VM_LOCKED Then check the increase VmLck field in /proc/pid/status(to 128k). When vma is set with different vm_flags, and the new vm_flags is with VM_LOCKED, it is not necessarily be a "new locked" vma. This patch corrects this bug by prevent mm->locked_vm from increment when old vm_flags is already VM_LOCKED. Link: http://lkml.kernel.org/r/1472554781-9835-3-git-send-email-wei.guo.simon@gmail.com Signed-off-by: Simon Guo <wei.guo.simon@gmail.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Alexey Klimov <klimov.linux@gmail.com> Cc: Eric B Munson <emunson@akamai.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Simon Guo <wei.guo.simon@gmail.com> Cc: Thierry Reding <treding@nvidia.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mlock: check against vma for actual mlock() sizeSimon Guo2016-10-071-0/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In do_mlock(), the check against locked memory limitation has a hole which will fail following cases at step 3): 1) User has a memory chunk from addressA with 50k, and user mem lock rlimit is 64k. 2) mlock(addressA, 30k) 3) mlock(addressA, 40k) The 3rd step should have been allowed since the 40k request is intersected with the previous 30k at step 2), and the 3rd step is actually for mlock on the extra 10k memory. This patch checks vma to caculate the actual "new" mlock size, if necessary, and ajust the logic to fix this issue. [akpm@linux-foundation.org: clean up comment layout] [wei.guo.simon@gmail.com: correct a typo in count_mm_mlocked_page_nr()] Link: http://lkml.kernel.org/r/1473325970-11393-2-git-send-email-wei.guo.simon@gmail.com Link: http://lkml.kernel.org/r/1472554781-9835-2-git-send-email-wei.guo.simon@gmail.com Signed-off-by: Simon Guo <wei.guo.simon@gmail.com> Cc: Alexey Klimov <klimov.linux@gmail.com> Cc: Eric B Munson <emunson@akamai.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Simon Guo <wei.guo.simon@gmail.com> Cc: Thierry Reding <treding@nvidia.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: move LRU lists to nodeMel Gorman2016-07-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmscan: move lru_lock to the nodeMel Gorman2016-07-281-5/+5
| | | | | | | | | | | | | | | | | | | | | Node-based reclaim requires node-based LRUs and locking. This is a preparation patch that just moves the lru_lock to the node so later patches are easier to review. It is a mechanical change but note this patch makes contention worse because the LRU lock is hotter and direct reclaim and kswapd can contend on the same lock even when reclaiming from different zones. Link: http://lkml.kernel.org/r/1467970510-21195-3-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make mmap_sem for write waits killable for mm syscallsMichal Hocko2016-05-231-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a follow up work for oom_reaper [1]. As the async OOM killing depends on oom_sem for read we would really appreciate if a holder for write didn't stood in the way. This patchset is changing many of down_write calls to be killable to help those cases when the writer is blocked and waiting for readers to release the lock and so help __oom_reap_task to process the oom victim. Most of the patches are really trivial because the lock is help from a shallow syscall paths where we can return EINTR trivially and allow the current task to die (note that EINTR will never get to the userspace as the task has fatal signal pending). Others seem to be easy as well as the callers are already handling fatal errors and bail and return to userspace which should be sufficient to handle the failure gracefully. I am not familiar with all those code paths so a deeper review is really appreciated. As this work is touching more areas which are not directly connected I have tried to keep the CC list as small as possible and people who I believed would be familiar are CCed only to the specific patches (all should have received the cover though). This patchset is based on linux-next and it depends on down_write_killable for rw_semaphores which got merged into tip locking/rwsem branch and it is merged into this next tree. I guess it would be easiest to route these patches via mmotm because of the dependency on the tip tree but if respective maintainers prefer other way I have no objections. I haven't covered all the mmap_write(mm->mmap_sem) instances here $ git grep "down_write(.*\<mmap_sem\>)" next/master | wc -l 98 $ git grep "down_write(.*\<mmap_sem\>)" | wc -l 62 I have tried to cover those which should be relatively easy to review in this series because this alone should be a nice improvement. Other places can be changed on top. [0] http://lkml.kernel.org/r/1456752417-9626-1-git-send-email-mhocko@kernel.org [1] http://lkml.kernel.org/r/1452094975-551-1-git-send-email-mhocko@kernel.org [2] http://lkml.kernel.org/r/1456750705-7141-1-git-send-email-mhocko@kernel.org This patch (of 18): This is the first step in making mmap_sem write waiters killable. It focuses on the trivial ones which are taking the lock early after entering the syscall and they are not changing state before. Therefore it is very easy to change them to use down_write_killable and immediately return with -EINTR. This will allow the waiter to pass away without blocking the mmap_sem which might be required to make a forward progress. E.g. the oom reaper will need the lock for reading to dismantle the OOM victim address space. The only tricky function in this patch is vm_mmap_pgoff which has many call sites via vm_mmap. To reduce the risk keep vm_mmap with the original non-killable semantic for now. vm_munmap callers do not bother checking the return value so open code it into the munmap syscall path for now for simplicity. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix mlock accoutingKirill A. Shutemov2016-01-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tetsuo Handa reported underflow of NR_MLOCK on munlock. Testcase: #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #define BASE ((void *)0x400000000000) #define SIZE (1UL << 21) int main(int argc, char *argv[]) { void *addr; system("grep Mlocked /proc/meminfo"); addr = mmap(BASE, SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED | MAP_FIXED, -1, 0); if (addr == MAP_FAILED) printf("mmap() failed\n"), exit(1); munmap(addr, SIZE); system("grep Mlocked /proc/meminfo"); return 0; } It happens on munlock_vma_page() due to unfortunate choice of nr_pages data type: __mod_zone_page_state(zone, NR_MLOCK, -nr_pages); For unsigned int nr_pages, implicitly casted to long in __mod_zone_page_state(), it becomes something around UINT_MAX. munlock_vma_page() usually called for THP as small pages go though pagevec. Let's make nr_pages signed int. Similar fixes in 6cdb18ad98a4 ("mm/vmstat: fix overflow in mod_zone_page_state()") used `long' type, but `int' here is OK for a count of the number of sub-pages in a huge page. Fixes: ff6a6da60b89 ("mm: accelerate munlock() treatment of THP pages") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Michel Lespinasse <walken@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> [4.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock.c: change can_do_mlock return value type to booleanWang Xiaoqiang2016-01-151-4/+4
| | | | | | | | | | | Since can_do_mlock only return 1 or 0, so make it boolean. No functional change. [akpm@linux-foundation.org: update declaration in mm.h] Signed-off-by: Wang Xiaoqiang <wangxq10@lzu.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: allow mlocked THP againKirill A. Shutemov2016-01-151-21/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before THP refcounting rework, THP was not allowed to cross VMA boundary. So, if we have THP and we split it, PG_mlocked can be safely transferred to small pages. With new THP refcounting and naive approach to mlocking we can end up with this scenario: 1. we have a mlocked THP, which belong to one VM_LOCKED VMA. 2. the process does munlock() on the *part* of the THP: - the VMA is split into two, one of them VM_LOCKED; - huge PMD split into PTE table; - THP is still mlocked; 3. split_huge_page(): - it transfers PG_mlocked to *all* small pages regrardless if it blong to any VM_LOCKED VMA. We probably could munlock() all small pages on split_huge_page(), but I think we have accounting issue already on step two. Instead of forbidding mlocked pages altogether, we just avoid mlocking PTE-mapped THPs and munlock THPs on split_huge_pmd(). This means PTE-mapped THPs will be on normal lru lists and will be split under memory pressure by vmscan. After the split vmscan will detect unevictable small pages and mlock them. With this approach we shouldn't hit situation like described above. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp, mlock: do not allow huge pages in mlocked areaKirill A. Shutemov2016-01-151-32/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With new refcounting THP can belong to several VMAs. This makes tricky to track THP pages, when they partially mlocked. It can lead to leaking mlocked pages to non-VM_LOCKED vmas and other problems. With this patch we will split all pages on mlock and avoid fault-in/collapse new THP in VM_LOCKED vmas. I've tried alternative approach: do not mark THP pages mlocked and keep them on normal LRUs. This way vmscan could try to split huge pages on memory pressure and free up subpages which doesn't belong to VM_LOCKED vmas. But this is user-visible change: we screw up Mlocked accouting reported in meminfo, so I had to leave this approach aside. We can bring something better later, but this should be good enough for now. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock.c: drop unneeded initialization in munlock_vma_pages_range()Alexey Klimov2016-01-141-1/+1
| | | | | | | | | | | Before usage page pointer initialized by NULL is reinitialized by follow_page_mask(). Drop useless init of page pointer in the beginning of loop. Signed-off-by: Alexey Klimov <klimov.linux@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mlock: add mlock flags to enable VM_LOCKONFAULT usageEric B Munson2015-11-051-13/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The previous patch introduced a flag that specified pages in a VMA should be placed on the unevictable LRU, but they should not be made present when the area is created. This patch adds the ability to set this state via the new mlock system calls. We add MLOCK_ONFAULT for mlock2 and MCL_ONFAULT for mlockall. MLOCK_ONFAULT will set the VM_LOCKONFAULT modifier for VM_LOCKED. MCL_ONFAULT should be used as a modifier to the two other mlockall flags. When used with MCL_CURRENT, all current mappings will be marked with VM_LOCKED | VM_LOCKONFAULT. When used with MCL_FUTURE, the mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. When used with both MCL_CURRENT and MCL_FUTURE, all current mappings and mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. Prior to this patch, mlockall() will unconditionally clear the mm->def_flags any time it is called without MCL_FUTURE. This behavior is maintained after adding MCL_ONFAULT. If a call to mlockall(MCL_FUTURE) is followed by mlockall(MCL_CURRENT), the mm->def_flags will be cleared and new VMAs will be unlocked. This remains true with or without MCL_ONFAULT in either mlockall() invocation. munlock() will unconditionally clear both vma flags. munlockall() unconditionally clears for VMA flags on all VMAs and in the mm->def_flags field. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce VM_LOCKONFAULTEric B Munson2015-11-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cost of faulting in all memory to be locked can be very high when working with large mappings. If only portions of the mapping will be used this can incur a high penalty for locking. For the example of a large file, this is the usage pattern for a large statical language model (probably applies to other statical or graphical models as well). For the security example, any application transacting in data that cannot be swapped out (credit card data, medical records, etc). This patch introduces the ability to request that pages are not pre-faulted, but are placed on the unevictable LRU when they are finally faulted in. The VM_LOCKONFAULT flag will be used together with VM_LOCKED and has no effect when set without VM_LOCKED. Setting the VM_LOCKONFAULT flag for a VMA will cause pages faulted into that VMA to be added to the unevictable LRU when they are faulted or if they are already present, but will not cause any missing pages to be faulted in. Exposing this new lock state means that we cannot overload the meaning of the FOLL_POPULATE flag any longer. Prior to this patch it was used to mean that the VMA for a fault was locked. This means we need the new FOLL_MLOCK flag to communicate the locked state of a VMA. FOLL_POPULATE will now only control if the VMA should be populated and in the case of VM_LOCKONFAULT, it will not be set. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mlock: add new mlock system callEric B Munson2015-11-051-0/+8
| | | | | | | | | | | | | | | | | | | | | | | With the refactored mlock code, introduce a new system call for mlock. The new call will allow the user to specify what lock states are being added. mlock2 is trivial at the moment, but a follow on patch will add a new mlock state making it useful. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mlock: refactor mlock, munlock, and munlockall codeEric B Munson2015-11-051-13/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mlock() allows a user to control page out of program memory, but this comes at the cost of faulting in the entire mapping when it is allocated. For large mappings where the entire area is not necessary this is not ideal. Instead of forcing all locked pages to be present when they are allocated, this set creates a middle ground. Pages are marked to be placed on the unevictable LRU (locked) when they are first used, but they are not faulted in by the mlock call. This series introduces a new mlock() system call that takes a flags argument along with the start address and size. This flags argument gives the caller the ability to request memory be locked in the traditional way, or to be locked after the page is faulted in. A new MCL flag is added to mirror the lock on fault behavior from mlock() in mlockall(). There are two main use cases that this set covers. The first is the security focussed mlock case. A buffer is needed that cannot be written to swap. The maximum size is known, but on average the memory used is significantly less than this maximum. With lock on fault, the buffer is guaranteed to never be paged out without consuming the maximum size every time such a buffer is created. The second use case is focussed on performance. Portions of a large file are needed and we want to keep the used portions in memory once accessed. This is the case for large graphical models where the path through the graph is not known until run time. The entire graph is unlikely to be used in a given invocation, but once a node has been used it needs to stay resident for further processing. Given these constraints we have a number of options. We can potentially waste a large amount of memory by mlocking the entire region (this can also cause a significant stall at startup as the entire file is read in). We can mlock every page as we access them without tracking if the page is already resident but this introduces large overhead for each access. The third option is mapping the entire region with PROT_NONE and using a signal handler for SIGSEGV to mprotect(PROT_READ) and mlock() the needed page. Doing this page at a time adds a significant performance penalty. Batching can be used to mitigate this overhead, but in order to safely avoid trying to mprotect pages outside of the mapping, the boundaries of each mapping to be used in this way must be tracked and available to the signal handler. This is precisely what the mm system in the kernel should already be doing. For mlock(MLOCK_ONFAULT) the user is charged against RLIMIT_MEMLOCK as if mlock(MLOCK_LOCKED) or mmap(MAP_LOCKED) was used, so when the VMA is created not when the pages are faulted in. For mlockall(MCL_ONFAULT) the user is charged as if MCL_FUTURE was used. This decision was made to keep the accounting checks out of the page fault path. To illustrate the benefit of this set I wrote a test program that mmaps a 5 GB file filled with random data and then makes 15,000,000 accesses to random addresses in that mapping. The test program was run 20 times for each setup. Results are reported for two program portions, setup and execution. The setup phase is calling mmap and optionally mlock on the entire region. For most experiments this is trivial, but it highlights the cost of faulting in the entire region. Results are averages across the 20 runs in milliseconds. mmap with mlock(MLOCK_LOCKED) on entire range: Setup avg: 8228.666 Processing avg: 8274.257 mmap with mlock(MLOCK_LOCKED) before each access: Setup avg: 0.113 Processing avg: 90993.552 mmap with PROT_NONE and signal handler and batch size of 1 page: With the default value in max_map_count, this gets ENOMEM as I attempt to change the permissions, after upping the sysctl significantly I get: Setup avg: 0.058 Processing avg: 69488.073 mmap with PROT_NONE and signal handler and batch size of 8 pages: Setup avg: 0.068 Processing avg: 38204.116 mmap with PROT_NONE and signal handler and batch size of 16 pages: Setup avg: 0.044 Processing avg: 29671.180 mmap with mlock(MLOCK_ONFAULT) on entire range: Setup avg: 0.189 Processing avg: 17904.899 The signal handler in the batch cases faulted in memory in two steps to avoid having to know the start and end of the faulting mapping. The first step covers the page that caused the fault as we know that it will be possible to lock. The second step speculatively tries to mlock and mprotect the batch size - 1 pages that follow. There may be a clever way to avoid this without having the program track each mapping to be covered by this handeler in a globally accessible structure, but I could not find it. It should be noted that with a large enough batch size this two step fault handler can still cause the program to crash if it reaches far beyond the end of the mapping. These results show that if the developer knows that a majority of the mapping will be used, it is better to try and fault it in at once, otherwise mlock(MLOCK_ONFAULT) is significantly faster. The performance cost of these patches are minimal on the two benchmarks I have tested (stream and kernbench). The following are the average values across 20 runs of stream and 10 runs of kernbench after a warmup run whose results were discarded. Avg throughput in MB/s from stream using 1000000 element arrays Test 4.2-rc1 4.2-rc1+lock-on-fault Copy: 10,566.5 10,421 Scale: 10,685 10,503.5 Add: 12,044.1 11,814.2 Triad: 12,064.8 11,846.3 Kernbench optimal load 4.2-rc1 4.2-rc1+lock-on-fault Elapsed Time 78.453 78.991 User Time 64.2395 65.2355 System Time 9.7335 9.7085 Context Switches 22211.5 22412.1 Sleeps 14965.3 14956.1 This patch (of 6): Extending the mlock system call is very difficult because it currently does not take a flags argument. A later patch in this set will extend mlock to support a middle ground between pages that are locked and faulted in immediately and unlocked pages. To pave the way for the new system call, the code needs some reorganization so that all the actual entry point handles is checking input and translating to VMA flags. Signed-off-by: Eric B Munson <emunson@akamai.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock: use offset_in_page macroAlexander Kuleshov2015-11-051-3/+3
| | | | | | | | | linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock.c: reorganize mlockall() return values and remove goto-out labelAlexey Klimov2015-11-051-5/+4
| | | | | | | | | | | | | | | In mlockall syscall wrapper after out-label for goto code just doing return. Remove goto out statements and return error values directly. Also instead of rewriting ret variable before every if-check move returns to 'error'-like path under if-check. Objdump asm listing showed me reducing by few asm lines. Object file size descreased from 220592 bytes to 220528 bytes for me (for aarch64). Signed-off-by: Alexey Klimov <klimov.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctxAndrea Arcangeli2015-09-041-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | vma->vm_userfaultfd_ctx is yet another vma parameter that vma_merge must be aware about so that we can merge vmas back like they were originally before arming the userfaultfd on some memory range. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Pavel Emelyanov <xemul@parallels.com> Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com> Cc: zhang.zhanghailiang@huawei.com Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Feiner <pfeiner@google.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move mm_populate()-related code to mm/gup.cKirill A. Shutemov2015-04-141-118/+0
| | | | | | | | | | | | | | | | | It's odd that we have populate_vma_page_range() and __mm_populate() in mm/mlock.c. It's implementation of generic memory population and mlocking is one of possible side effect, if VM_LOCKED is set. __get_user_pages() is core of the implementation. Let's move the code into mm/gup.c. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move gup() -> posix mlock() error conversion out of __mm_populateKirill A. Shutemov2015-04-141-4/+7
| | | | | | | | | | | | | This is praparation to moving mm_populate()-related code out of mm/mlock.c. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: rename __mlock_vma_pages_range() to populate_vma_page_range()Kirill A. Shutemov2015-04-141-6/+6
| | | | | | | | | | | | | | | | | | | __mlock_vma_pages_range() doesn't necessarily mlock pages. It depends on vma flags. The same codepath is used for MAP_POPULATE. Let's rename __mlock_vma_pages_range() to populate_vma_page_range(). This patch also drops mlock_vma_pages_range() references from documentation. It has gone in cea10a19b797 ("mm: directly use __mlock_vma_pages_range() in find_extend_vma()"). Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: rename FOLL_MLOCK to FOLL_POPULATEKirill A. Shutemov2015-04-141-1/+1
| | | | | | | | | | | | | | | | | | After commit a1fde08c74e9 ("VM: skip the stack guard page lookup in get_user_pages only for mlock") FOLL_MLOCK has lost its original meaning: we don't necessarily mlock the page if the flags is set -- we also take VM_LOCKED into consideration. Since we use the same codepath for __mm_populate(), let's rename FOLL_MLOCK to FOLL_POPULATE. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: reorder can_do_mlock to fix audit denialJeff Vander Stoep2015-03-121-2/+2
| | | | | | | | | | | | | | | | | | | | | A userspace call to mmap(MAP_LOCKED) may result in the successful locking of memory while also producing a confusing audit log denial. can_do_mlock checks capable and rlimit. If either of these return positive can_do_mlock returns true. The capable check leads to an LSM hook used by apparmour and selinux which produce the audit denial. Reordering so rlimit is checked first eliminates the denial on success, only recording a denial when the lock is unsuccessful as a result of the denial. Signed-off-by: Jeff Vander Stoep <jeffv@google.com> Acked-by: Nick Kralevich <nnk@google.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Paul Cassella <cassella@cray.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-10-131-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - changes related to No-CBs CPUs and NO_HZ_FULL - RCU-tasks implementation - torture-test updates - miscellaneous fixes - locktorture updates - RCU documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) workqueue: Use cond_resched_rcu_qs macro workqueue: Add quiescent state between work items locktorture: Cleanup header usage locktorture: Cannot hold read and write lock locktorture: Fix __acquire annotation for spinlock irq locktorture: Support rwlocks rcu: Eliminate deadlock between CPU hotplug and expedited grace periods locktorture: Document boot/module parameters rcutorture: Rename rcutorture_runnable parameter locktorture: Add test scenario for rwsem_lock locktorture: Add test scenario for mutex_lock locktorture: Make torture scripting account for new _runnable name locktorture: Introduce torture context locktorture: Support rwsems locktorture: Add infrastructure for torturing read locks torture: Address race in module cleanup locktorture: Make statistics generic locktorture: Teach about lock debugging locktorture: Support mutexes locktorture: Add documentation ...
| * rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loopsPaul E. McKenney2014-09-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU-tasks requires the occasional voluntary context switch from CPU-bound in-kernel tasks. In some cases, this requires instrumenting cond_resched(). However, there is some reluctance to countenance unconditionally instrumenting cond_resched() (see http://lwn.net/Articles/603252/), so this commit creates a separate cond_resched_rcu_qs() that may be used in place of cond_resched() in locations prone to long-duration in-kernel looping. This commit currently instruments only RCU-tasks. Future possibilities include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce IPI usage. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* | mm: use VM_BUG_ON_MM where possibleSasha Levin2014-10-091-1/+1
| | | | | | | | | | | | | | | | Dump the contents of the relevant struct_mm when we hit the bug condition. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMASasha Levin2014-10-091-2/+2
|/ | | | | | | | | | | | | | | | | | | | Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract more information when they trigger. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: describe mmap_sem rules for __lock_page_or_retry() and callersPaul Cassella2014-08-061-1/+8
| | | | | | | | | | | | | | | | Add a comment describing the circumstances in which __lock_page_or_retry() will or will not release the mmap_sem when returning 0. Add comments to lock_page_or_retry()'s callers (filemap_fault(), do_swap_page()) noting the impact on VM_FAULT_RETRY returns. Add comments on up the call tree, particularly replacing the false "We return with mmap_sem still held" comments. Signed-off-by: Paul Cassella <cassella@cray.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: try_to_unmap_cluster() should lock_page() before mlockingVlastimil Babka2014-04-071-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A BUG_ON(!PageLocked) was triggered in mlock_vma_page() by Sasha Levin fuzzing with trinity. The call site try_to_unmap_cluster() does not lock the pages other than its check_page parameter (which is already locked). The BUG_ON in mlock_vma_page() is not documented and its purpose is somewhat unclear, but apparently it serializes against page migration, which could otherwise fail to transfer the PG_mlocked flag. This would not be fatal, as the page would be eventually encountered again, but NR_MLOCK accounting would become distorted nevertheless. This patch adds a comment to the BUG_ON in mlock_vma_page() and munlock_vma_page() to that effect. The call site try_to_unmap_cluster() is fixed so that for page != check_page, trylock_page() is attempted (to avoid possible deadlocks as we already have check_page locked) and mlock_vma_page() is performed only upon success. If the page lock cannot be obtained, the page is left without PG_mlocked, which is again not a problem in the whole unevictable memory design. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Bob Liu <bob.liu@oracle.com> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Michel Lespinasse <walken@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGESasha Levin2014-01-231-2/+2
| | | | | | | | | | | | | | | | | | | | Most of the VM_BUG_ON assertions are performed on a page. Usually, when one of these assertions fails we'll get a BUG_ON with a call stack and the registers. I've recently noticed based on the requests to add a small piece of code that dumps the page to various VM_BUG_ON sites that the page dump is quite useful to people debugging issues in mm. This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON. [akpm@linux-foundation.org: fix up includes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: munlock: fix potential race with THP page splitVlastimil Babka2014-01-231-44/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit ff6a6da60b89 ("mm: accelerate munlock() treatment of THP pages") munlock skips tail pages of a munlocked THP page. There is some attempt to prevent bad consequences of racing with a THP page split, but code inspection indicates that there are two problems that may lead to a non-fatal, yet wrong outcome. First, __split_huge_page_refcount() copies flags including PageMlocked from the head page to the tail pages. Clearing PageMlocked by munlock_vma_page() in the middle of this operation might result in part of tail pages left with PageMlocked flag. As the head page still appears to be a THP page until all tail pages are processed, munlock_vma_page() might think it munlocked the whole THP page and skip all the former tail pages. Before ff6a6da60, those pages would be cleared in further iterations of munlock_vma_pages_range(), but NR_MLOCK would still become undercounted (related the next point). Second, NR_MLOCK accounting is based on call to hpage_nr_pages() after the PageMlocked is cleared. The accounting might also become inconsistent due to race with __split_huge_page_refcount() - undercount when HUGE_PMD_NR is subtracted, but some tail pages are left with PageMlocked set and counted again (only possible before ff6a6da60) - overcount when hpage_nr_pages() sees a normal page (split has already finished), but the parallel split has meanwhile cleared PageMlocked from additional tail pages This patch prevents both problems via extending the scope of lru_lock in munlock_vma_page(). This is convenient because: - __split_huge_page_refcount() takes lru_lock for its whole operation - munlock_vma_page() typically takes lru_lock anyway for page isolation As this becomes a second function where page isolation is done with lru_lock already held, factor this out to a new __munlock_isolate_lru_page() function and clean up the code around. [akpm@linux-foundation.org: avoid a coding-style ugly] Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock: prepare params outside critical regionDavidlohr Bueso2014-01-211-7/+11
| | | | | | | | | | | | | | All mlock related syscalls prepare lock limits, lengths and start parameters with the mmap_sem held. Move this logic outside of the critical region. For the case of mlock, continue incrementing the amount already locked by mm->locked_vm with the rwsem taken. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: Michel Lespinasse <walken@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: munlock: fix deadlock in __munlock_pagevec()Vlastimil Babka2014-01-021-5/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 7225522bb429 ("mm: munlock: batch non-THP page isolation and munlock+putback using pagevec" introduced __munlock_pagevec() to speed up munlock by holding lru_lock over multiple isolated pages. Pages that fail to be isolated are put_page()d immediately, also within the lock. This can lead to deadlock when __munlock_pagevec() becomes the holder of the last page pin and put_page() leads to __page_cache_release() which also locks lru_lock. The deadlock has been observed by Sasha Levin using trinity. This patch avoids the deadlock by deferring put_page() operations until lru_lock is released. Another pagevec (which is also used by later phases of the function is reused to gather the pages for put_page() operation. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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