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* HWPOISON: comment dirty swapcache pagesWu Fengguang2009-12-161-0/+4
| | | | | | | AK: Improve comment Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
* ksm: let shared pages be swappableHugh Dickins2009-12-151-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Initial implementation for swapping out KSM's shared pages: add page_referenced_ksm() and try_to_unmap_ksm(), which rmap.c calls when faced with a PageKsm page. Most of what's needed can be got from the rmap_items listed from the stable_node of the ksm page, without discovering the actual vma: so in this patch just fake up a struct vma for page_referenced_one() or try_to_unmap_one(), then refine that in the next patch. Add VM_NONLINEAR to ksm_madvise()'s list of exclusions: it has always been implicit there (being only set with VM_SHARED, already excluded), but let's make it explicit, to help justify the lack of nonlinear unmap. Rely on the page lock to protect against concurrent modifications to that page's node of the stable tree. The awkward part is not swapout but swapin: do_swap_page() and page_add_anon_rmap() now have to allow for new possibilities - perhaps a ksm page still in swapcache, perhaps a swapcache page associated with one location in one anon_vma now needed for another location or anon_vma. (And the vma might even be no longer VM_MERGEABLE when that happens.) ksm_might_need_to_copy() checks for that case, and supplies a duplicate page when necessary, simply leaving it to a subsequent pass of ksmd to rediscover the identity and merge them back into one ksm page. Disappointingly primitive: but the alternative would have to accumulate unswappable info about the swapped out ksm pages, limiting swappability. Remove page_add_ksm_rmap(): page_add_anon_rmap() now has to allow for the particular case it was handling, so just use it instead. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: sigbus instead of abusing oomHugh Dickins2009-12-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When do_nonlinear_fault() realizes that the page table must have been corrupted for it to have been called, it does print_bad_pte() and returns ... VM_FAULT_OOM, which is hard to understand. It made some sense when I did it for 2.6.15, when do_page_fault() just killed the current process; but nowadays it lets the OOM killer decide who to kill - so page table corruption in one process would be liable to kill another. Change it to return VM_FAULT_SIGBUS instead: that doesn't guarantee that the process will be killed, but is good enough for such a rare abnormality, accompanied as it is by the "BUG: Bad page map" message. And recent HWPOISON work has copied that code into do_swap_page(), when it finds an impossible swap entry: fix that to VM_FAULT_SIGBUS too. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Nick Piggin <npiggin@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Andi Kleen <andi@firstfloor.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* swap_info: swap count continuationsHugh Dickins2009-12-151-3/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Swap is duplicated (reference count incremented by one) whenever the same swap page is inserted into another mm (when forking finds a swap entry in place of a pte, or when reclaim unmaps a pte to insert the swap entry). swap_info_struct's vmalloc'ed swap_map is the array of these reference counts: but what happens when the unsigned short (or unsigned char since the preceding patch) is full? (and its high bit is kept for a cache flag) We then lose track of it, never freeing, leaving it in use until swapoff: at which point we _hope_ that a single pass will have found all instances, assume there are no more, and will lose user data if we're wrong. Swapping of KSM pages has not yet been enabled; but it is implemented, and makes it very easy for a user to overflow the maximum swap count: possible with ordinary process pages, but unlikely, even when pid_max has been raised from PID_MAX_DEFAULT. This patch implements swap count continuations: when the count overflows, a continuation page is allocated and linked to the original vmalloc'ed map page, and this used to hold the continuation counts for that entry and its neighbours. These continuation pages are seldom referenced: the common paths all work on the original swap_map, only referring to a continuation page when the low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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>
* Merge branch 'hwpoison-2.6.32' of ↵Linus Torvalds2009-10-291-1/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 * 'hwpoison-2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: HWPOISON: fix invalid page count in printk output HWPOISON: Allow schedule_on_each_cpu() from keventd HWPOISON: fix/proc/meminfo alignment HWPOISON: fix oops on ksm pages HWPOISON: Fix page count leak in hwpoison late kill in do_swap_page HWPOISON: return early on non-LRU pages HWPOISON: Add brief hwpoison description to Documentation HWPOISON: Clean up PR_MCE_KILL interface
| * HWPOISON: Fix page count leak in hwpoison late kill in do_swap_pageAndi Kleen2009-10-191-1/+2
| | | | | | | | | | | | | | | | | | | | | | When returning due to a poisoned page drop the page count. It wasn't a fatal problem because noone cares about the page count on a poisoned page (except when it wraps), but it's cleaner to fix it. Pointed out by Linus. Signed-off-by: Andi Kleen <ak@linux.intel.com>
* | mm: don't call pte_unmap() against an improper pteDaisuke Nishimura2009-10-291-4/+7
|/ | | | | | | | | | | | | | | | | | | | There are some places where we do like: pte = pte_map(); do { (do break in some conditions) } while (pte++, ...); pte_unmap(pte - 1); But if the loop breaks at the first loop, pte_unmap() unmaps invalid pte. This patch is a fix for this problem. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Reviewd-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2009-09-241-59/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: truncate: use new helpers truncate: new helpers fs: fix overflow in sys_mount() for in-kernel calls fs: Make unload_nls() NULL pointer safe freeze_bdev: grab active reference to frozen superblocks freeze_bdev: kill bd_mount_sem exofs: remove BKL from super operations fs/romfs: correct error-handling code vfs: seq_file: add helpers for data filling vfs: remove redundant position check in do_sendfile vfs: change sb->s_maxbytes to a loff_t vfs: explicitly cast s_maxbytes in fiemap_check_ranges libfs: return error code on failed attr set seq_file: return a negative error code when seq_path_root() fails. vfs: optimize touch_time() too vfs: optimization for touch_atime() vfs: split generic_forget_inode() so that hugetlbfs does not have to copy it fs/inode.c: add dev-id and inode number for debugging in init_special_inode() libfs: make simple_read_from_buffer conventional
| * truncate: new helpersnpiggin@suse.de2009-09-241-59/+3
| | | | | | | | | | | | | | | | | | | | Introduce new truncate helpers truncate_pagecache and inode_newsize_ok. vmtruncate is also consolidated from mm/memory.c and mm/nommu.c and into mm/truncate.c. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'hwpoison' of ↵Linus Torvalds2009-09-241-3/+21
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 * 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: (21 commits) HWPOISON: Enable error_remove_page on btrfs HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs HWPOISON: Add madvise() based injector for hardware poisoned pages v4 HWPOISON: Enable error_remove_page for NFS HWPOISON: Enable .remove_error_page for migration aware file systems HWPOISON: The high level memory error handler in the VM v7 HWPOISON: Add PR_MCE_KILL prctl to control early kill behaviour per process HWPOISON: shmem: call set_page_dirty() with locked page HWPOISON: Define a new error_remove_page address space op for async truncation HWPOISON: Add invalidate_inode_page HWPOISON: Refactor truncate to allow direct truncating of page v2 HWPOISON: check and isolate corrupted free pages v2 HWPOISON: Handle hardware poisoned pages in try_to_unmap HWPOISON: Use bitmask/action code for try_to_unmap behaviour HWPOISON: x86: Add VM_FAULT_HWPOISON handling to x86 page fault handler v2 HWPOISON: Add poison check to page fault handling HWPOISON: Add basic support for poisoned pages in fault handler v3 HWPOISON: Add new SIGBUS error codes for hardware poison signals HWPOISON: Add support for poison swap entries v2 HWPOISON: Export some rmap vma locking to outside world ...
| * HWPOISON: Add poison check to page fault handlingAndi Kleen2009-09-161-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | Bail out early when hardware poisoned pages are found in page fault handling. Since they are poisoned they should not be mapped freshly into processes, because that would cause another (potentially deadly) machine check This is generally handled in the same way as OOM, just a different error code is returned to the architecture code. v2: Do a page unlock if needed (Fengguang Wu) Signed-off-by: Andi Kleen <ak@linux.intel.com>
| * HWPOISON: Add basic support for poisoned pages in fault handler v3Andi Kleen2009-09-161-3/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | - Add a new VM_FAULT_HWPOISON error code to handle_mm_fault. Right now architectures have to explicitely enable poison page support, so this is forward compatible to all architectures. They only need to add it when they enable poison page support. - Add poison page handling in swap in fault code v2: Add missing delayacct_clear_flag (Hidehiro Kawai) v3: Really use delayacct_clear_flag (Hidehiro Kawai) Signed-off-by: Andi Kleen <ak@linux.intel.com>
* | mm: move highest_memmap_pfnHugh Dickins2009-09-221-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move highest_memmap_pfn __read_mostly from page_alloc.c next to zero_pfn __read_mostly in memory.c: to help them share a cacheline, since they're very often tested together in vm_normal_page(). Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: ZERO_PAGE without PTE_SPECIALHugh Dickins2009-09-221-11/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reinstate anonymous use of ZERO_PAGE to all architectures, not just to those which __HAVE_ARCH_PTE_SPECIAL: as suggested by Nick Piggin. Contrary to how I'd imagined it, there's nothing ugly about this, just a zero_pfn test built into one or another block of vm_normal_page(). But the MIPS ZERO_PAGE-of-many-colours case demands is_zero_pfn() and my_zero_pfn() inlines. Reinstate its mremap move_pte() shuffling of ZERO_PAGEs we did from 2.6.17 to 2.6.19? Not unless someone shouts for that: it would have to take vm_flags to weed out some cases. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Rik van Riel <riel@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: FOLL flags for GUP flagsHugh Dickins2009-09-221-25/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __get_user_pages() has been taking its own GUP flags, then processing them into FOLL flags for follow_page(). Though oddly named, the FOLL flags are more widely used, so pass them to __get_user_pages() now. Sorry, VM flags, VM_FAULT flags and FAULT_FLAGs are still distinct. (The patch to __get_user_pages() looks peculiar, with both gup_flags and foll_flags: the gup_flags remain constant; but as before there's an exceptional case, out of scope of the patch, in which foll_flags per page have FOLL_WRITE masked off.) Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: reinstate ZERO_PAGEHugh Dickins2009-09-221-9/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KAMEZAWA Hiroyuki has observed customers of earlier kernels taking advantage of the ZERO_PAGE: which we stopped do_anonymous_page() from using in 2.6.24. And there were a couple of regression reports on LKML. Following suggestions from Linus, reinstate do_anonymous_page() use of the ZERO_PAGE; but this time avoid dirtying its struct page cacheline with (map)count updates - let vm_normal_page() regard it as abnormal. Use it only on arches which __HAVE_ARCH_PTE_SPECIAL (x86, s390, sh32, most powerpc): that's not essential, but minimizes additional branches (keeping them in the unlikely pte_special case); and incidentally excludes mips (some models of which needed eight colours of ZERO_PAGE to avoid costly exceptions). Don't be fanatical about avoiding ZERO_PAGE updates: get_user_pages() callers won't want to make exceptions for it, so increment its count there. Changes to mlock and migration? happily seems not needed. In most places it's quicker to check pfn than struct page address: prepare a __read_mostly zero_pfn for that. Does get_dump_page() still need its ZERO_PAGE check? probably not, but keep it anyway. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: fix anonymous dirtyingHugh Dickins2009-09-221-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | do_anonymous_page() has been wrong to dirty the pte regardless. If it's not going to mark the pte writable, then it won't help to mark it dirty here, and clogs up memory with pages which will need swap instead of being thrown away. Especially wrong if no overcommit is chosen, and this vma is not yet VM_ACCOUNTed - we could exceed the limit and OOM despite no overcommit. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: <stable@kernel.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: follow_hugetlb_page flagsHugh Dickins2009-09-221-6/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | follow_hugetlb_page() shouldn't be guessing about the coredump case either: pass the foll_flags down to it, instead of just the write bit. Remove that obscure huge_zeropage_ok() test. The decision is easy, though unlike the non-huge case - here vm_ops->fault is always set. But we know that a fault would serve up zeroes, unless there's already a hugetlbfs pagecache page to back the range. (Alternatively, since hugetlb pages aren't swapped out under pressure, you could save more dump space by arguing that a page not yet faulted into this process cannot be relevant to the dump; but that would be more surprising.) Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: FOLL_DUMP replace FOLL_ANONHugh Dickins2009-09-221-31/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The "FOLL_ANON optimization" and its use_zero_page() test have caused confusion and bugs: why does it test VM_SHARED? for the very good but unsatisfying reason that VMware crashed without. As we look to maybe reinstating anonymous use of the ZERO_PAGE, we need to sort this out. Easily done: it's silly for __get_user_pages() and follow_page() to be guessing whether it's safe to assume that they're being used for a coredump (which can take a shortcut snapshot where other uses must handle a fault) - just tell them with GUP_FLAGS_DUMP and FOLL_DUMP. get_dump_page() doesn't even want a ZERO_PAGE: an error suits fine. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: add get_dump_pageHugh Dickins2009-09-221-1/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In preparation for the next patch, add a simple get_dump_page(addr) interface for the CONFIG_ELF_CORE dumpers to use, instead of calling get_user_pages() directly. They're not interested in errors: they just want to use holes as much as possible, to save space and make sure that the data is aligned where the headers said it would be. Oh, and don't use that horrid DUMP_SEEK(off) macro! Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: remove unused GUP flagsHugh Dickins2009-09-221-10/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | GUP_FLAGS_IGNORE_VMA_PERMISSIONS and GUP_FLAGS_IGNORE_SIGKILL were flags added solely to prevent __get_user_pages() from doing some of what it usually does, in the munlock case: we can now remove them. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: drop unneeded double negationsJohannes Weiner2009-09-221-1/+1
| | | | | | | | | | | | | | | | | | | | Remove double negations where the operand is already boolean. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | ksm: fix deadlock with munlock in exit_mmapAndrea Arcangeli2009-09-221-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rawhide users have reported hang at startup when cryptsetup is run: the same problem can be simply reproduced by running a program int main() { mlockall(MCL_CURRENT | MCL_FUTURE); return 0; } The problem is that exit_mmap() applies munlock_vma_pages_all() to clean up VM_LOCKED areas, and its current implementation (stupidly) tries to fault in absent pages, for example where PROT_NONE prevented them being faulted in when mlocking. Whereas the "ksm: fix oom deadlock" patch, knowing there's a race by which KSM might try to fault in pages after exit_mmap() had finally zapped the range, backs out of such faults doing nothing when its ksm_test_exit() notices mm_users 0. So revert that part of "ksm: fix oom deadlock" which moved the ksm_exit() call from before exit_mmap() to the middle of exit_mmap(); and remove those ksm_test_exit() checks from the page fault paths, so allowing the munlocking to proceed without interference. ksm_exit, if there are rmap_items still chained on this mm slot, takes mmap_sem write side: so preventing KSM from working on an mm while exit_mmap runs. And KSM will bail out as soon as it notices that mm_users is already zero, thanks to its internal ksm_test_exit checks. So that when a task is killed by OOM killer or the user, KSM will not indefinitely prevent it from running exit_mmap to release its memory. This does break a part of what "ksm: fix oom deadlock" was trying to achieve. When unmerging KSM (echo 2 >/sys/kernel/mm/ksm), and even when ksmd itself has to cancel a KSM page, it is possible that the first OOM-kill victim would be the KSM process being faulted: then its memory won't be freed until a second victim has been selected (freeing memory for the unmerging fault to complete). But the OOM killer is already liable to kill a second victim once the intended victim's p->mm goes to NULL: so there's not much point in rejecting this KSM patch before fixing that OOM behaviour. It is very much more important to allow KSM users to boot up, than to haggle over an unlikely and poorly supported OOM case. We also intend to fix munlocking to not fault pages: at which point this patch _could_ be reverted; though that would be controversial, so we hope to find a better solution. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Justin M. Forbes <jforbes@redhat.com> Acked-for-now-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | ksm: fix oom deadlockHugh Dickins2009-09-221-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's a now-obvious deadlock in KSM's out-of-memory handling: imagine ksmd or KSM_RUN_UNMERGE handling, holding ksm_thread_mutex, trying to allocate a page to break KSM in an mm which becomes the OOM victim (quite likely in the unmerge case): it's killed and goes to exit, and hangs there waiting to acquire ksm_thread_mutex. Clearly we must not require ksm_thread_mutex in __ksm_exit, simple though that made everything else: perhaps use mmap_sem somehow? And part of the answer lies in the comments on unmerge_ksm_pages: __ksm_exit should also leave all the rmap_item removal to ksmd. But there's a fundamental problem, that KSM relies upon mmap_sem to guarantee the consistency of the mm it's dealing with, yet exit_mmap tears down an mm without taking mmap_sem. And bumping mm_users won't help at all, that just ensures that the pages the OOM killer assumes are on their way to being freed will not be freed. The best answer seems to be, to move the ksm_exit callout from just before exit_mmap, to the middle of exit_mmap: after the mm's pages have been freed (if the mmu_gather is flushed), but before its page tables and vma structures have been freed; and down_write,up_write mmap_sem there to serialize with KSM's own reliance on mmap_sem. But KSM then needs to be careful, whenever it downs mmap_sem, to check that the mm is not already exiting: there's a danger of using find_vma on a layout that's being torn apart, or writing into page tables which have been freed for reuse; and even do_anonymous_page and __do_fault need to check they're not being called by break_ksm to reinstate a pte after zap_pte_range has zapped that page table. Though it might be clearer to add an exiting flag, set while holding mmap_sem in __ksm_exit, that wouldn't cover the issue of reinstating a zapped pte. All we need is to check whether mm_users is 0 - but must remember that ksmd may detect that before __ksm_exit is reached. So, ksm_test_exit(mm) added to comment such checks on mm->mm_users. __ksm_exit now has to leave clearing up the rmap_items to ksmd, that needs ksm_thread_mutex; but shift the exiting mm just after the ksm_scan cursor so that it will soon be dealt with. __ksm_enter raise mm_count to hold the mm_struct, ksmd's exit processing (exactly like its processing when it finds all VM_MERGEABLEs unmapped) mmdrop it, similar procedure for KSM_RUN_UNMERGE (which has stopped ksmd). But also give __ksm_exit a fast path: when there's no complication (no rmap_items attached to mm and it's not at the ksm_scan cursor), it can safely do all the exiting work itself. This is not just an optimization: when ksmd is not running, the raised mm_count would otherwise leak mm_structs. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | ksm: identify PageKsm pagesHugh Dickins2009-09-221-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KSM will need to identify its kernel merged pages unambiguously, and /proc/kpageflags will probably like to do so too. Since KSM will only be substituting anonymous pages, statistics are best preserved by making a PageKsm page a special PageAnon page: one with no anon_vma. But KSM then needs its own page_add_ksm_rmap() - keep it in ksm.h near PageKsm; and do_wp_page() must COW them, unlike singly mapped PageAnons. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Izik Eidus <ieidus@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Avi Kivity <avi@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | ksm: no debug in page_dup_rmap()Hugh Dickins2009-09-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | page_dup_rmap(), used on each mapped page when forking, was originally just an inline atomic_inc of mapcount. 2.6.22 added CONFIG_DEBUG_VM out-of-line checks to it, which would need to be ever-so-slightly complicated to allow for the PageKsm() we're about to define. But I think these checks never caught anything. And if it's coding errors we're worried about, such checks should be in page_remove_rmap() too, not just when forking; whereas if it's pagetable corruption we're worried about, then they shouldn't be limited to CONFIG_DEBUG_VM. Oh, just revert page_dup_rmap() to an inline atomic_inc of mapcount. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Izik Eidus <ieidus@redhat.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Avi Kivity <avi@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | ksm: add mmu_notifier set_pte_at_notify()Izik Eidus2009-09-221-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KSM is a linux driver that allows dynamicly sharing identical memory pages between one or more processes. Unlike tradtional page sharing that is made at the allocation of the memory, ksm do it dynamicly after the memory was created. Memory is periodically scanned; identical pages are identified and merged. The sharing is made in a transparent way to the processes that use it. Ksm is highly important for hypervisors (kvm), where in production enviorments there might be many copys of the same data data among the host memory. This kind of data can be: similar kernels, librarys, cache, and so on. Even that ksm was wrote for kvm, any userspace application that want to use it to share its data can try it. Ksm may be useful for any application that might have similar (page aligment) data strctures among the memory, ksm will find this data merge it to one copy, and even if it will be changed and thereforew copy on writed, ksm will merge it again as soon as it will be identical again. Another reason to consider using ksm is the fact that it might simplify alot the userspace code of application that want to use shared private data, instead that the application will mange shared area, ksm will do this for the application, and even write to this data will be allowed without any synchinization acts from the application. Ksm was designed to be a loadable module that doesn't change the VM code of linux. This patch: The set_pte_at_notify() macro allows setting a pte in the shadow page table directly, instead of flushing the shadow page table entry and then getting vmexit to set it. It uses a new change_pte() callback to do so. set_pte_at_notify() is an optimization for kvm, and other users of mmu_notifiers, for COW pages. It is useful for kvm when ksm is used, because it allows kvm not to have to receive vmexit and only then map the ksm page into the shadow page table, but instead map it directly at the same time as Linux maps the page into the host page table. Users of mmu_notifiers who don't implement new mmu_notifier_change_pte() callback will just receive the mmu_notifier_invalidate_page() callback. Signed-off-by: Izik Eidus <ieidus@redhat.com> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Avi Kivity <avi@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | headers: taskstats_kern.h trimAlexey Dobriyan2009-09-181-0/+1
|/ | | | | | | | Remove net/genetlink.h inclusion, now sched.c won't be recompiled because of some networking changes. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Pass virtual address to [__]p{te,ud,md}_free_tlb()Benjamin Herrenschmidt2009-07-271-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | mm: Pass virtual address to [__]p{te,ud,md}_free_tlb() Upcoming paches to support the new 64-bit "BookE" powerpc architecture will need to have the virtual address corresponding to PTE page when freeing it, due to the way the HW table walker works. Basically, the TLB can be loaded with "large" pages that cover the whole virtual space (well, sort-of, half of it actually) represented by a PTE page, and which contain an "indirect" bit indicating that this TLB entry RPN points to an array of PTEs from which the TLB can then create direct entries. Thus, in order to invalidate those when PTE pages are deleted, we need the virtual address to pass to tlbilx or tlbivax instructions. The old trick of sticking it somewhere in the PTE page struct page sucks too much, the address is almost readily available in all call sites and almost everybody implemets these as macros, so we may as well add the argument everywhere. I added it to the pmd and pud variants for consistency. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: David Howells <dhowells@redhat.com> [MN10300 & FRV] Acked-by: Nick Piggin <npiggin@suse.de> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> [s390] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* clarify get_user_pages() prototypePeter Zijlstra2009-06-251-14/+12
| | | | | | | | | Currently the 4th parameter of get_user_pages() is called len, but its in pages, not bytes. Rename the thing to nr_pages to avoid future confusion. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: pass mm to grab_swap_tokenHugh Dickins2009-06-231-1/+1
| | | | | | | | | | | | | | | | | | | | If a kthread happens to use get_user_pages() on an mm (as KSM does), there's a chance that it will end up trying to read in a swap page, then oops in grab_swap_token() because the kthread has no mm: GUP passes down the right mm, so grab_swap_token() ought to be using it. We have not identified a stronger case than KSM's daemon (not yet in mainline), but the issue must have come up before, since RHEL has included a fix for this for years (though a different fix, they just back out of grab_swap_token if current->mm is unset: which is what we first proposed, but using the right mm here seems more correct). Reported-by: Izik Eidus <ieidus@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: 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: don't rely on flags coincidenceHugh Dickins2009-06-231-2/+4
| | | | | | | | | | | | Indeed FOLL_WRITE matches FAULT_FLAG_WRITE, matches GUP_FLAGS_WRITE, and it's tempting to devise a set of Grand Unified Paging flags; but not today. So until then, let's rely upon the compiler to spot the coincidence, "rather than have that subtle dependency and a comment for it" - as you remarked in another context yesterday. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Move FAULT_FLAG_xyz into handle_mm_fault() callersLinus Torvalds2009-06-211-4/+4
| | | | | | | | | | This allows the callers to now pass down the full set of FAULT_FLAG_xyz flags to handle_mm_fault(). All callers have been (mechanically) converted to the new calling convention, there's almost certainly room for architectures to clean up their code and then add FAULT_FLAG_RETRY when that support is added. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove internal use of 'write_access' in mm/memory.cLinus Torvalds2009-06-211-21/+21
| | | | | | | | | | | | | | | | The fault handling routines really want more fine-grained flags than a single "was it a write fault" boolean - the callers will want to set flags like "you can return a retry error" etc. And that's actually how the VM works internally, but right now the top-level fault handling functions in mm/memory.c all pass just the 'write_access' boolean around. This switches them over to pass around the FAULT_FLAG_xyzzy 'flags' variable instead. The 'write_access' calling convention still exists for the exported 'handle_mm_fault()' function, but that is next. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce follow_pfn()Johannes Weiner2009-06-161-0/+29
| | | | | | | | | | | | | | Analoguous to follow_phys(), add a helper that looks up the PFN at a user virtual address in an IO mapping or a raw PFN mapping. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Acked-by: Magnus Damm <magnus.damm@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: use generic follow_pte() in follow_phys()Johannes Weiner2009-06-161-31/+5
| | | | | | | | | | | Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Acked-by: Magnus Damm <magnus.damm@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce follow_pte()Johannes Weiner2009-06-161-0/+37
| | | | | | | | | | | | | | A generic readonly page table lookup helper to map an address space and an address from it to a pte. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@infradead.org> Acked-by: Magnus Damm <magnus.damm@gmail.com> Cc: Hans Verkuil <hverkuil@xs4all.nl> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: clean up get_user_pages_fast() documentationNick Piggin2009-06-161-0/+50
| | | | | | | | | | | | | | Move more documentation for get_user_pages_fast into the new kerneldoc comment. Add some comments for get_user_pages as well. Also, move get_user_pages_fast declaration up to get_user_pages. It wasn't there initially because it was once a static inline function. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Andy Grover <andy.grover@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: close page_mkwrite racesNick Piggin2009-05-021-32/+76
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change page_mkwrite to allow implementations to return with the page locked, and also change it's callers (in page fault paths) to hold the lock until the page is marked dirty. This allows the filesystem to have full control of page dirtying events coming from the VM. Rather than simply hold the page locked over the page_mkwrite call, we call page_mkwrite with the page unlocked and allow callers to return with it locked, so filesystems can avoid LOR conditions with page lock. The problem with the current scheme is this: a filesystem that wants to associate some metadata with a page as long as the page is dirty, will perform this manipulation in its ->page_mkwrite. It currently then must return with the page unlocked and may not hold any other locks (according to existing page_mkwrite convention). In this window, the VM could write out the page, clearing page-dirty. The filesystem has no good way to detect that a dirty pte is about to be attached, so it will happily write out the page, at which point, the filesystem may manipulate the metadata to reflect that the page is no longer dirty. It is not always possible to perform the required metadata manipulation in ->set_page_dirty, because that function cannot block or fail. The filesystem may need to allocate some data structure, for example. And the VM cannot mark the pte dirty before page_mkwrite, because page_mkwrite is allowed to fail, so we must not allow any window where the page could be written to if page_mkwrite does fail. This solution of holding the page locked over the 3 critical operations (page_mkwrite, setting the pte dirty, and finally setting the page dirty) closes out races nicely, preventing page cleaning for writeout being initiated in that window. This provides the filesystem with a strong synchronisation against the VM here. - Sage needs this race closed for ceph filesystem. - Trond for NFS (http://bugzilla.kernel.org/show_bug.cgi?id=12913). - I need it for fsblock. - I suspect other filesystems may need it too (eg. btrfs). - I have converted buffer.c to the new locking. Even simple block allocation under dirty pages might be susceptible to i_size changing under partial page at the end of file (we also have a buffer.c-side problem here, but it cannot be fixed properly without this patch). - Other filesystems (eg. NFS, maybe btrfs) will need to change their page_mkwrite functions themselves. [ This also moves page_mkwrite another step closer to fault, which should eventually allow page_mkwrite to be moved into ->fault, and thus avoiding a filesystem calldown and page lock/unlock cycle in __do_fault. ] [akpm@linux-foundation.org: fix derefs of NULL ->mapping] Cc: Sage Weil <sage@newdream.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix pageref leak in do_swap_page()Johannes Weiner2009-05-021-2/+2
| | | | | | | | | | | | | | | By the time the memory cgroup code is notified about a swapin we already hold a reference on the fault page. If the cgroup callback fails make sure to unlock AND release the page reference which was taken by lookup_swap_cach(), or we leak the reference. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: page_mkwrite change prototype to match faultNick Piggin2009-04-011-4/+22
| | | | | | | | | | | | | | | | | | | | | | | | Change the page_mkwrite prototype to take a struct vm_fault, and return VM_FAULT_xxx flags. There should be no functional change. This makes it possible to return much more detailed error information to the VM (and also can provide more information eg. virtual_address to the driver, which might be important in some special cases). This is required for a subsequent fix. And will also make it easier to merge page_mkwrite() with fault() in future. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <joel.becker@oracle.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Cc: Felix Blyakher <felixb@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add comment why mark_page_accessed() would be better than pte_mkyoung() ↵KOSAKI Motohiro2009-04-011-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | in follow_page() At first look, mark_page_accessed() in follow_page() seems a bit strange. It seems pte_mkyoung() would be better consistent with other kernel code. However, it is intentional. The commit log said: ------------------------------------------------ commit 9e45f61d69be9024a2e6bef3831fb04d90fac7a8 Author: akpm <akpm> Date: Fri Aug 15 07:24:59 2003 +0000 [PATCH] Use mark_page_accessed() in follow_page() Touching a page via follow_page() counts as a reference so we should be either setting the referenced bit in the pte or running mark_page_accessed(). Altering the pte is tricky because we haven't implemented an atomic pte_mkyoung(). And mark_page_accessed() is better anyway because it has more aging state: it can move the page onto the active list. BKrev: 3f3c8acbplT8FbwBVGtth7QmnqWkIw ------------------------------------------------ The atomic issue is still true nowadays. adding comment help to understand code intention and it would be better. [akpm@linux-foundation.org: clarify text] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: don't call mark_page_accessed() in do_swap_page()KOSAKI Motohiro2009-04-011-2/+0
| | | | | | | | | | | | | | | | commit bf3f3bc5e734706730c12a323f9b2068052aa1f0 (mm: don't mark_page_accessed in fault path) only remove the mark_page_accessed() in filemap_fault(). Therefore, swap-backed pages and file-backed pages have inconsistent behavior. mark_page_accessed() should be removed from do_swap_page(). Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.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>
* VM, x86, PAT: add a new vm flag to track full pfnmap at mmapPallipadi, Venkatesh2009-03-141-2/+2
| | | | | | | | | | | | | | Impact: cleanup Add a new vm flag VM_PFN_AT_MMAP to identify a PFNMAP that is fully mapped with remap_pfn_range. Patch removes the overloading of VM_INSERTPAGE from the earlier patch. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Nick Piggin <npiggin@suse.de> LKML-Reference: <20090313233543.GA19909@linux-os.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* VM, x86, PAT: Change is_linear_pfn_mapping to not use vm_pgoffPallipadi, Venkatesh2009-03-131-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: fix false positive PAT warnings - also fix VirtalBox hang Use of vma->vm_pgoff to identify the pfnmaps that are fully mapped at mmap time is broken. vm_pgoff is set by generic mmap code even for cases where drivers are setting up the mappings at the fault time. The problem was originally reported here: http://marc.info/?l=linux-kernel&m=123383810628583&w=2 Change is_linear_pfn_mapping logic to overload VM_INSERTPAGE flag along with VM_PFNMAP to mean full PFNMAP setup at mmap time. Problem also tracked at: http://bugzilla.kernel.org/show_bug.cgi?id=12800 Reported-by: Thomas Hellstrom <thellstrom@vmware.com> Tested-by: Frans Pop <elendil@planet.nl> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha>@intel.com> Cc: Nick Piggin <npiggin@suse.de> Cc: "ebiederm@xmission.com" <ebiederm@xmission.com> Cc: <stable@kernel.org> # only for 2.6.29.1, not .28 LKML-Reference: <20090313004527.GA7176@linux-os.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* do_wp_page: fix regression with execute in placeCarsten Otte2009-02-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | Fix do_wp_page for VM_MIXEDMAP mappings. In the case where pfn_valid returns 0 for a pfn at the beginning of do_wp_page and the mapping is not shared writable, the code branches to label `gotten:' with old_page == NULL. In case the vma is locked (vma->vm_flags & VM_LOCKED), lock_page, clear_page_mlock, and unlock_page try to access the old_page. This patch checks whether old_page is valid before it is dereferenced. The regression was introduced by "mlock: mlocked pages are unevictable" (commit b291f000393f5a0b679012b39d79fbc85c018233). Signed-off-by: Carsten Otte <cotte@de.ibm.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: <stable@kernel.org> [2.6.28.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* x86 PAT: change track_pfn_vma_new to take pgprot_t pointer paramvenkatesh.pallipadi@intel.com2009-01-131-3/+4
| | | | | | | | | | | | | Impact: cleanup Change the protection parameter for track_pfn_vma_new() into a pgprot_t pointer. Subsequent patch changes the x86 PAT handling to return a compatible memtype in pgprot_t, if what was requested cannot be allowed due to conflicts. No fuctionality change in this patch. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* x86 PAT: remove PFNMAP type on track_pfn_vma_new() errorvenkatesh.pallipadi@intel.com2009-01-131-1/+7
| | | | | | | | | | | | | | | | | | | | | Impact: fix (harmless) double-free of memtype entries and avoid warning On track_pfn_vma_new() failure, reset the vm_flags so that there will be no second cleanup happening when upper level routines call unmap_vmas(). This patch fixes part of the bug reported here: http://marc.info/?l=linux-kernel&m=123108883716357&w=2 Specifically the error message: X:5010 freeing invalid memtype d0000000-d0101000 Is due to multiple frees on error path, will not happen with the patch below. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep, mm: fix might_fault() annotationPeter Zijlstra2009-01-121-0/+9
| | | | | | | | | | | Some code (nfs/sunrpc) uses socket ops on kernel memory while holding the mmap_sem, this is safe because kernel memory doesn't get paged out, therefore we'll never actually fault, and the might_fault() annotations will generate false positives. Reported-by: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* memcg: fix swap accounting leakKAMEZAWA Hiroyuki2009-01-081-5/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix swapin charge operation of memcg. Now, memcg has hooks to swap-out operation and checks SwapCache is really unused or not. That check depends on contents of struct page. I.e. If PageAnon(page) && page_mapped(page), the page is recoginized as still-in-use. Now, reuse_swap_page() calles delete_from_swap_cache() before establishment of any rmap. Then, in followinig sequence (Page fault with WRITE) try_charge() (charge += PAGESIZE) commit_charge() (Check page_cgroup is used or not..) reuse_swap_page() -> delete_from_swapcache() -> mem_cgroup_uncharge_swapcache() (charge -= PAGESIZE) ...... New charge is uncharged soon.... To avoid this, move commit_charge() after page_mapcount() goes up to 1. By this, try_charge() (usage += PAGESIZE) reuse_swap_page() (may usage -= PAGESIZE if PCG_USED is set) commit_charge() (If page_cgroup is not marked as PCG_USED, add new charge.) Accounting will be correct. Changelog (v2) -> (v3) - fixed invalid charge to swp_entry==0. - updated documentation. Changelog (v1) -> (v2) - fixed comment. [nishimura@mxp.nes.nec.co.jp: swap accounting leak doc fix] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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