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* mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flagsDan Williams2017-11-031-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The mmap(2) syscall suffers from the ABI anti-pattern of not validating unknown flags. However, proposals like MAP_SYNC need a mechanism to define new behavior that is known to fail on older kernels without the support. Define a new MAP_SHARED_VALIDATE flag pattern that is guaranteed to fail on all legacy mmap implementations. It is worth noting that the original proposal was for a standalone MAP_VALIDATE flag. However, when that could not be supported by all archs Linus observed: I see why you *think* you want a bitmap. You think you want a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC etc, so that people can do ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_SYNC, fd, 0); and "know" that MAP_SYNC actually takes. And I'm saying that whole wish is bogus. You're fundamentally depending on special semantics, just make it explicit. It's already not portable, so don't try to make it so. Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value of 0x3, and make people do ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE | MAP_SYNC, fd, 0); and then the kernel side is easier too (none of that random garbage playing games with looking at the "MAP_VALIDATE bit", but just another case statement in that map type thing. Boom. Done. Similar to ->fallocate() we also want the ability to validate the support for new flags on a per ->mmap() 'struct file_operations' instance basis. Towards that end arrange for flags to be generically validated against a mmap_supported_flags exported by 'struct file_operations'. By default all existing flags are implicitly supported, but new flags require MAP_SHARED_VALIDATE and per-instance-opt-in. Cc: Jan Kara <jack@suse.cz> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Suggested-by: Christoph Hellwig <hch@lst.de> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* mm/memory_hotplug: define find_{smallest|biggest}_section_pfn as unsigned longYASUAKI ISHIMATSU2017-10-031-2/+2
| | | | | | | | | | | | | | | | | | | | find_{smallest|biggest}_section_pfn()s find the smallest/biggest section and return the pfn of the section. But the functions are defined as int. So the functions always return 0x00000000 - 0xffffffff. It means if memory address is over 16TB, the functions does not work correctly. To handle 64 bit value, the patch defines find_{smallest|biggest}_section_pfn() as unsigned long. Fixes: 815121d2b5cd ("memory_hotplug: clear zone when removing the memory") Link: http://lkml.kernel.org/r/d9d5593a-d0a4-c4be-ab08-493df59a85c6@gmail.com Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.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/memory_hotplug: change pfn_to_section_nr/section_nr_to_pfn macro to ↵YASUAKI ISHIMATSU2017-10-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | inline function pfn_to_section_nr() and section_nr_to_pfn() are defined as macro. pfn_to_section_nr() has no issue even if it is defined as macro. But section_nr_to_pfn() has overflow issue if sec is defined as int. section_nr_to_pfn() just shifts sec by PFN_SECTION_SHIFT. If sec is defined as unsigned long, section_nr_to_pfn() returns pfn as 64 bit value. But if sec is defined as int, section_nr_to_pfn() returns pfn as 32 bit value. __remove_section() calculates start_pfn using section_nr_to_pfn() and scn_nr defined as int. So if hot-removed memory address is over 16TB, overflow issue occurs and section_nr_to_pfn() does not calculate correct pfn. To make callers use proper arg, the patch changes the macros to inline functions. Fixes: 815121d2b5cd ("memory_hotplug: clear zone when removing the memory") Link: http://lkml.kernel.org/r/e643a387-e573-6bbf-d418-c60c8ee3d15e@gmail.com Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.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, page_alloc: add scheduling point to memmap_init_zoneMichal Hocko2017-10-031-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | memmap_init_zone gets a pfn range to initialize and it can be really large resulting in a soft lockup on non-preemptible kernels NMI watchdog: BUG: soft lockup - CPU#31 stuck for 23s! [kworker/u642:5:1720] [...] task: ffff88ecd7e902c0 ti: ffff88eca4e50000 task.ti: ffff88eca4e50000 RIP: move_pfn_range_to_zone+0x185/0x1d0 [...] Call Trace: devm_memremap_pages+0x2c7/0x430 pmem_attach_disk+0x2fd/0x3f0 [nd_pmem] nvdimm_bus_probe+0x64/0x110 [libnvdimm] driver_probe_device+0x1f7/0x420 bus_for_each_drv+0x52/0x80 __device_attach+0xb0/0x130 bus_probe_device+0x87/0xa0 device_add+0x3fc/0x5f0 nd_async_device_register+0xe/0x40 [libnvdimm] async_run_entry_fn+0x43/0x150 process_one_work+0x14e/0x410 worker_thread+0x116/0x490 kthread+0xc7/0xe0 ret_from_fork+0x3f/0x70 Fix this by adding a scheduling point once per page block. Link: http://lkml.kernel.org/r/20170918121410.24466-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Johannes Thumshirn <jthumshirn@suse.de> Tested-by: Johannes Thumshirn <jthumshirn@suse.de> Cc: Dan Williams <dan.j.williams@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, memory_hotplug: add scheduling point to __add_pagesMichal Hocko2017-10-031-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm, memory_hotplug: fix few soft lockups in memory hotadd". Johannes has noticed few soft lockups when adding a large nvdimm device. All of them were caused by a long loop without any explicit cond_resched which is a problem for !PREEMPT kernels. The fix is quite straightforward. Just make sure that cond_resched gets called from time to time. This patch (of 3): __add_pages gets a pfn range to add and there is no upper bound for a single call. This is usually a memory block aligned size for the regular memory hotplug - smaller sizes are usual for memory balloning drivers, or the whole NUMA node for physical memory online. There is no explicit scheduling point in that code path though. This can lead to long latencies while __add_pages is executed and we have even seen a soft lockup report during nvdimm initialization with !PREEMPT kernel NMI watchdog: BUG: soft lockup - CPU#11 stuck for 23s! [kworker/u641:3:832] [...] Workqueue: events_unbound async_run_entry_fn task: ffff881809270f40 ti: ffff881809274000 task.ti: ffff881809274000 RIP: _raw_spin_unlock_irqrestore+0x11/0x20 RSP: 0018:ffff881809277b10 EFLAGS: 00000286 [...] Call Trace: sparse_add_one_section+0x13d/0x18e __add_pages+0x10a/0x1d0 arch_add_memory+0x4a/0xc0 devm_memremap_pages+0x29d/0x430 pmem_attach_disk+0x2fd/0x3f0 [nd_pmem] nvdimm_bus_probe+0x64/0x110 [libnvdimm] driver_probe_device+0x1f7/0x420 bus_for_each_drv+0x52/0x80 __device_attach+0xb0/0x130 bus_probe_device+0x87/0xa0 device_add+0x3fc/0x5f0 nd_async_device_register+0xe/0x40 [libnvdimm] async_run_entry_fn+0x43/0x150 process_one_work+0x14e/0x410 worker_thread+0x116/0x490 kthread+0xc7/0xe0 ret_from_fork+0x3f/0x70 DWARF2 unwinder stuck at ret_from_fork+0x3f/0x70 Fix this by adding cond_resched once per each memory section in the given pfn range. Each section is constant amount of work which itself is not too expensive but many of them will just add up. Link: http://lkml.kernel.org/r/20170918121410.24466-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Johannes Thumshirn <jthumshirn@suse.de> Tested-by: Johannes Thumshirn <jthumshirn@suse.de> Cc: Dan Williams <dan.j.williams@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcontrol: use vmalloc fallback for large kmem memcg arraysJohannes Weiner2017-10-032-13/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/device-public-memory: fix edge case in _vm_normal_page()Reza Arbab2017-10-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With device public pages at the end of my memory space, I'm getting output from _vm_normal_page(): BUG: Bad page map in process migrate_pages pte:c0800001ffff0d06 pmd:f95d3000 addr:00007fff89330000 vm_flags:00100073 anon_vma:c0000000fa899320 mapping: (null) index:7fff8933 file: (null) fault: (null) mmap: (null) readpage: (null) CPU: 0 PID: 13963 Comm: migrate_pages Tainted: P B OE 4.14.0-rc1-wip #155 Call Trace: dump_stack+0xb0/0xf4 (unreliable) print_bad_pte+0x28c/0x340 _vm_normal_page+0xc0/0x140 zap_pte_range+0x664/0xc10 unmap_page_range+0x318/0x670 unmap_vmas+0x74/0xe0 exit_mmap+0xe8/0x1f0 mmput+0xac/0x1f0 do_exit+0x348/0xcd0 do_group_exit+0x5c/0xf0 SyS_exit_group+0x1c/0x20 system_call+0x58/0x6c The pfn causing this is the very last one. Correct the bounds check accordingly. Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache coherent with CPU") Link: http://lkml.kernel.org/r/1506092178-20351-1-git-send-email-arbab@linux.vnet.ibm.com Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix data corruption caused by lazyfree pageShaohua Li2017-10-031-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MADV_FREE clears pte dirty bit and then marks the page lazyfree (clear SwapBacked). There is no lock to prevent the page is added to swap cache between these two steps by page reclaim. If page reclaim finds such page, it will simply add the page to swap cache without pageout the page to swap because the page is marked as clean. Next time, page fault will read data from the swap slot which doesn't have the original data, so we have a data corruption. To fix issue, we mark the page dirty and pageout the page. However, we shouldn't dirty all pages which is clean and in swap cache. swapin page is swap cache and clean too. So we only dirty page which is added into swap cache in page reclaim, which shouldn't be swapin page. As Minchan suggested, simply dirty the page in add_to_swap can do the job. Fixes: 802a3a92ad7a ("mm: reclaim MADV_FREE pages") Link: http://lkml.kernel.org/r/08c84256b007bf3f63c91d94383bd9eb6fee2daa.1506446061.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Reported-by: Artem Savkov <asavkov@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: avoid marking swap cached page as lazyfreeShaohua Li2017-10-031-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MADV_FREE clears pte dirty bit and then marks the page lazyfree (clear SwapBacked). There is no lock to prevent the page is added to swap cache between these two steps by page reclaim. Page reclaim could add the page to swap cache and unmap the page. After page reclaim, the page is added back to lru. At that time, we probably start draining per-cpu pagevec and mark the page lazyfree. So the page could be in a state with SwapBacked cleared and PG_swapcache set. Next time there is a refault in the virtual address, do_swap_page can find the page from swap cache but the page has PageSwapCache false because SwapBacked isn't set, so do_swap_page will bail out and do nothing. The task will keep running into fault handler. Fixes: 802a3a92ad7a ("mm: reclaim MADV_FREE pages") Link: http://lkml.kernel.org/r/6537ef3814398c0073630b03f176263bc81f0902.1506446061.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Reported-by: Artem Savkov <asavkov@redhat.com> Tested-by: Artem Savkov <asavkov@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: have filemap_check_and_advance_wb_err clear AS_EIO/AS_ENOSPCJeff Layton2017-10-031-0/+8
| | | | | | | | | | | | | | | | | | | | | | Eryu noticed that he could sometimes get a leftover error reported when it shouldn't be on fsync with ext2 and non-journalled ext4. The problem is that writeback_single_inode still uses filemap_fdatawait. That picks up a previously set AS_EIO flag, which would ordinarily have been cleared before. Since we're mostly using this function as a replacement for filemap_check_errors, have filemap_check_and_advance_wb_err clear AS_EIO and AS_ENOSPC when reporting an error. That should allow the new function to better emulate the behavior of the old with respect to these flags. Link: http://lkml.kernel.org/r/20170922133331.28812-1-jlayton@kernel.org Signed-off-by: Jeff Layton <jlayton@redhat.com> Reported-by: Eryu Guan <eguan@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix RODATA_TEST failure "rodata_test: test data was not read only"Christophe Leroy2017-10-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | On powerpc, RODATA_TEST fails with message the following messages: Freeing unused kernel memory: 528K rodata_test: test data was not read only This is because GCC allocates it to .data section: c0695034 g O .data 00000004 rodata_test_data Since commit 056b9d8a7692 ("mm: remove rodata_test_data export, add pr_fmt"), rodata_test_data is used only inside rodata_test.c By declaring it static, it gets properly allocated into .rodata section instead of .data: c04df710 l O .rodata 00000004 rodata_test_data Fixes: 056b9d8a7692 ("mm: remove rodata_test_data export, add pr_fmt") Link: http://lkml.kernel.org/r/20170921093729.1080368AC1@po15668-vm-win7.idsi0.si.c-s.fr Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Kees Cook <keescook@chromium.org> Cc: Jinbum Park <jinb.park7@gmail.com> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: David Laight <David.Laight@ACULAB.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: meminit: mark init_reserved_page as __meminitArnd Bergmann2017-10-031-1/+1
| | | | | | | | | | | | | | | | | | | | The function is called from __meminit context and calls other __meminit functions but isn't it self mark as such today: WARNING: vmlinux.o(.text.unlikely+0x4516): Section mismatch in reference from the function init_reserved_page() to the function .meminit.text:early_pfn_to_nid() The function init_reserved_page() references the function __meminit early_pfn_to_nid(). This is often because init_reserved_page lacks a __meminit annotation or the annotation of early_pfn_to_nid is wrong. On most compilers, we don't notice this because the function gets inlined all the time. Adding __meminit here fixes the harmless warning for the old versions and is generally the correct annotation. Link: http://lkml.kernel.org/r/20170915193149.901180-1-arnd@arndb.de Fixes: 7e18adb4f80b ("mm: meminit: initialise remaining struct pages in parallel with kswapd") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* z3fold: fix stale list handlingVitaly Wool2017-10-031-4/+2
| | | | | | | | | | | | Fix the situation when clear_bit() is called for page->private before the page pointer is actually assigned. While at it, remove work_busy() check because it is costly and does not give 100% guarantee anyway. Signed-off-by: Vitaly Wool <vitalywool@gmail.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: <Oleksiy.Avramchenko@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm,compaction: serialize waitqueue_active() checks (for real)Davidlohr Bueso2017-10-031-8/+5
| | | | | | | | | | | | | | | | | | Andrea brought to my attention that the L->{L,S} guarantees are completely bogus for this case. I was looking at the diagram, from the offending commit, when that _is_ the race, we had the load reordered already. What we need is at least S->L semantics, thus simply use wq_has_sleeper() to serialize the call for good. Link: http://lkml.kernel.org/r/20170914175313.GB811@linux-80c1.suse Fixes: 46acef048a6 (mm,compaction: serialize waitqueue_active() checks) Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Andrea Parri <parri.andrea@gmail.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/memcg: avoid page count check for zone deviceJérôme Glisse2017-10-031-1/+2
| | | | | | | | | | | | | | | | | Fix for 4.14, zone device page always have an elevated refcount of one and thus page count sanity check in uncharge_page() is inappropriate for them. [mhocko@suse.com: nano-optimize VM_BUG_ON in uncharge_page] Link: http://lkml.kernel.org/r/20170914190011.5217-1-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Evgeny Baskakov <ebaskakov@nvidia.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, memcg: remove hotplug locking from try_chargeMichal Hocko2017-10-031-5/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following lockdep splat has been noticed during LTP testing ====================================================== WARNING: possible circular locking dependency detected 4.13.0-rc3-next-20170807 #12 Not tainted ------------------------------------------------------ a.out/4771 is trying to acquire lock: (cpu_hotplug_lock.rw_sem){++++++}, at: [<ffffffff812b4668>] drain_all_stock.part.35+0x18/0x140 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<ffffffff8106eb35>] __do_page_fault+0x175/0x530 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&mm->mmap_sem){++++++}: lock_acquire+0xc9/0x230 __might_fault+0x70/0xa0 _copy_to_user+0x23/0x70 filldir+0xa7/0x110 xfs_dir2_sf_getdents.isra.10+0x20c/0x2c0 [xfs] xfs_readdir+0x1fa/0x2c0 [xfs] xfs_file_readdir+0x30/0x40 [xfs] iterate_dir+0x17a/0x1a0 SyS_getdents+0xb0/0x160 entry_SYSCALL_64_fastpath+0x1f/0xbe -> #2 (&type->i_mutex_dir_key#3){++++++}: lock_acquire+0xc9/0x230 down_read+0x51/0xb0 lookup_slow+0xde/0x210 walk_component+0x160/0x250 link_path_walk+0x1a6/0x610 path_openat+0xe4/0xd50 do_filp_open+0x91/0x100 file_open_name+0xf5/0x130 filp_open+0x33/0x50 kernel_read_file_from_path+0x39/0x80 _request_firmware+0x39f/0x880 request_firmware_direct+0x37/0x50 request_microcode_fw+0x64/0xe0 reload_store+0xf7/0x180 dev_attr_store+0x18/0x30 sysfs_kf_write+0x44/0x60 kernfs_fop_write+0x113/0x1a0 __vfs_write+0x37/0x170 vfs_write+0xc7/0x1c0 SyS_write+0x58/0xc0 do_syscall_64+0x6c/0x1f0 return_from_SYSCALL_64+0x0/0x7a -> #1 (microcode_mutex){+.+.+.}: lock_acquire+0xc9/0x230 __mutex_lock+0x88/0x960 mutex_lock_nested+0x1b/0x20 microcode_init+0xbb/0x208 do_one_initcall+0x51/0x1a9 kernel_init_freeable+0x208/0x2a7 kernel_init+0xe/0x104 ret_from_fork+0x2a/0x40 -> #0 (cpu_hotplug_lock.rw_sem){++++++}: __lock_acquire+0x153c/0x1550 lock_acquire+0xc9/0x230 cpus_read_lock+0x4b/0x90 drain_all_stock.part.35+0x18/0x140 try_charge+0x3ab/0x6e0 mem_cgroup_try_charge+0x7f/0x2c0 shmem_getpage_gfp+0x25f/0x1050 shmem_fault+0x96/0x200 __do_fault+0x1e/0xa0 __handle_mm_fault+0x9c3/0xe00 handle_mm_fault+0x16e/0x380 __do_page_fault+0x24a/0x530 do_page_fault+0x30/0x80 page_fault+0x28/0x30 other info that might help us debug this: Chain exists of: cpu_hotplug_lock.rw_sem --> &type->i_mutex_dir_key#3 --> &mm->mmap_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(&type->i_mutex_dir_key#3); lock(&mm->mmap_sem); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** 2 locks held by a.out/4771: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8106eb35>] __do_page_fault+0x175/0x530 #1: (percpu_charge_mutex){+.+...}, at: [<ffffffff812b4c97>] try_charge+0x397/0x6e0 The problem is very similar to the one fixed by commit a459eeb7b852 ("mm, page_alloc: do not depend on cpu hotplug locks inside the allocator"). We are taking hotplug locks while we can be sitting on top of basically arbitrary locks. This just calls for problems. We can get rid of {get,put}_online_cpus, fortunately. We do not have to be worried about races with memory hotplug because drain_local_stock, which is called from both the WQ draining and the memory hotplug contexts, is always operating on the local cpu stock with IRQs disabled. The only thing to be careful about is that the target memcg doesn't vanish while we are still in drain_all_stock so take a reference on it. Link: http://lkml.kernel.org/r/20170913090023.28322-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Artem Savkov <asavkov@redhat.com> Tested-by: Artem Savkov <asavkov@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, oom_reaper: skip mm structs with mmu notifiersMichal Hocko2017-10-031-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andrea has noticed that the oom_reaper doesn't invalidate the range via mmu notifiers (mmu_notifier_invalidate_range_start/end) and that can corrupt the memory of the kvm guest for example. tlb_flush_mmu_tlbonly already invokes mmu notifiers but that is not sufficient as per Andrea: "mmu_notifier_invalidate_range cannot be used in replacement of mmu_notifier_invalidate_range_start/end. For KVM mmu_notifier_invalidate_range is a noop and rightfully so. A MMU notifier implementation has to implement either ->invalidate_range method or the invalidate_range_start/end methods, not both. And if you implement invalidate_range_start/end like KVM is forced to do, calling mmu_notifier_invalidate_range in common code is a noop for KVM. For those MMU notifiers that can get away only implementing ->invalidate_range, the ->invalidate_range is implicitly called by mmu_notifier_invalidate_range_end(). And only those secondary MMUs that share the same pagetable with the primary MMU (like AMD iommuv2) can get away only implementing ->invalidate_range" As the callback is allowed to sleep and the implementation is out of hand of the MM it is safer to simply bail out if there is an mmu notifier registered. In order to not fail too early make the mm_has_notifiers check under the oom_lock and have a little nap before failing to give the current oom victim some more time to exit. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170913113427.2291-1-mhocko@kernel.org Fixes: aac453635549 ("mm, oom: introduce oom reaper") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* z3fold: fix potential race in z3fold_reclaim_pageVitaly Wool2017-10-031-1/+3
| | | | | | | | | | | | | | | | | | It is possible that on a (partially) unsuccessful page reclaim, kref_put() called in z3fold_reclaim_page() does not yield page release, but the page is released shortly afterwards by another thread. Then z3fold_reclaim_page() would try to list_add() that (released) page again which is obviously a bug. To avoid that, spin_lock() has to be taken earlier, before the kref_put() call mentioned earlier. Link: http://lkml.kernel.org/r/20170913162937.bfff21c7d12b12a5f47639fd@gmail.com Signed-off-by: Vitaly Wool <vitalywool@gmail.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: <Oleksiy.Avramchenko@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb, soft_offline: save compound page order before page migrationAlexandru Moise2017-10-031-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a bug in madvise() where if you'd try to soft offline a hugepage via madvise(), while walking the address range you'd end up, using the wrong page offset due to attempting to get the compound order of a former but presently not compound page, due to dissolving the huge page (since commit c3114a84f7f9: "mm: hugetlb: soft-offline: dissolve source hugepage after successful migration"). As a result I ended up with all my free pages except one being offlined. Link: http://lkml.kernel.org/r/20170912204306.GA12053@gmail.com Fixes: c3114a84f7f9 ("mm: hugetlb: soft-offline: dissolve source hugepage after successful migration") Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Shaohua Li <shli@fb.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: fix unlocked iteration over vmas in cmp_and_merge_page()Kirill Tkhai2017-10-031-1/+4
| | | | | | | | | | | | | | | | | | | | In this place mm is unlocked, so vmas or list may change. Down read mmap_sem to protect them from modifications. Link: http://lkml.kernel.org/r/150512788393.10691.8868381099691121308.stgit@localhost.localdomain Fixes: e86c59b1b12d ("mm/ksm: improve deduplication of zero pages with colouring") Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: zhong jiang <zhongjiang@huawei.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> 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>
* percpu: fix iteration to prevent skipping over blockDennis Zhou2017-09-281-0/+4
| | | | | | | | | | | | | | | | | | | | The iterator functions pcpu_next_md_free_region and pcpu_next_fit_region use the block offset to determine if they have checked the area in the prior iteration. However, this causes an issue when the block offset is greater than subsequent block contig hints. If within the iterator it moves to check subsequent blocks, it may fail in the second predicate due to the block offset not being cleared. Thus, this causes the allocator to skip over blocks leading to false failures when allocating from the reserved chunk. While this happens in the general case as well, it will only fail if it cannot allocate a new chunk. This patch resets the block offset to 0 to pass the second predicate when checking subseqent blocks within the iterator function. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reported-and-tested-by: Luis Henriques <lhenriques@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* percpu: fix starting offset for chunk statistics traversalDennis Zhou2017-09-271-1/+1
| | | | | | | | | | | This patch fixes the starting offset used when scanning chunks to compute the chunk statistics. The value start_offset (and end_offset) are managed in bytes while the traversal occurs over bits. Thus for the reserved and dynamic chunk, it may incorrectly skip over the initial allocations. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* fs: Fix page cache inconsistency when mixing buffered and AIO DIOLukas Czerner2017-09-251-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when mixing buffered reads and asynchronous direct writes it is possible to end up with the situation where we have stale data in the page cache while the new data is already written to disk. This is permanent until the affected pages are flushed away. Despite the fact that mixing buffered and direct IO is ill-advised it does pose a thread for a data integrity, is unexpected and should be fixed. Fix this by deferring completion of asynchronous direct writes to a process context in the case that there are mapped pages to be found in the inode. Later before the completion in dio_complete() invalidate the pages in question. This ensures that after the completion the pages in the written area are either unmapped, or populated with up-to-date data. Also do the same for the iomap case which uses iomap_dio_complete() instead. This has a side effect of deferring the completion to a process context for every AIO DIO that happens on inode that has pages mapped. However since the consensus is that this is ill-advised practice the performance implication should not be a problem. This was based on proposal from Jeff Moyer, thanks! Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Merge branch 'work.read_write' of ↵Linus Torvalds2017-09-141-7/+17
|\ | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull nowait read support from Al Viro: "Support IOCB_NOWAIT for buffered reads and block devices" * 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: block_dev: support RFW_NOWAIT on block device nodes fs: support RWF_NOWAIT for buffered reads fs: support IOCB_NOWAIT in generic_file_buffered_read fs: pass iocb to do_generic_file_read
| * fs: support IOCB_NOWAIT in generic_file_buffered_readMilosz Tanski2017-09-041-0/+9
| | | | | | | | | | | | | | | | | | | | | | Allow generic_file_buffered_read to bail out early instead of waiting for the page lock or reading a page if IOCB_NOWAIT is specified. Signed-off-by: Milosz Tanski <milosz@adfin.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Sage Weil <sage@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * fs: pass iocb to do_generic_file_readChristoph Hellwig2017-09-041-7/+8
| | | | | | | | | | | | | | | | | | And rename it to the more descriptive generic_file_buffered_read while at it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'work.set_fs' of ↵Linus Torvalds2017-09-141-6/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull more set_fs removal from Al Viro: "Christoph's 'use kernel_read and friends rather than open-coding set_fs()' series" * 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: unexport vfs_readv and vfs_writev fs: unexport vfs_read and vfs_write fs: unexport __vfs_read/__vfs_write lustre: switch to kernel_write gadget/f_mass_storage: stop messing with the address limit mconsole: switch to kernel_read btrfs: switch write_buf to kernel_write net/9p: switch p9_fd_read to kernel_write mm/nommu: switch do_mmap_private to kernel_read serial2002: switch serial2002_tty_write to kernel_{read/write} fs: make the buf argument to __kernel_write a void pointer fs: fix kernel_write prototype fs: fix kernel_read prototype fs: move kernel_read to fs/read_write.c fs: move kernel_write to fs/read_write.c autofs4: switch autofs4_write to __kernel_write ashmem: switch to ->read_iter
| * | mm/nommu: switch do_mmap_private to kernel_readChristoph Hellwig2017-09-041-6/+1
| |/ | | | | | | | | | | | | | | Instead of playing with the address limit. This also gains us validation of the kvec and proper atime updates. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'akpm' (patches from Andrew)Linus Torvalds2017-09-143-3/+3
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge misc fixes from Andrew Morton: "A few leftovers" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: mm, page_owner: skip unnecessary stack_trace entries arm64: stacktrace: avoid listing stacktrace functions in stacktrace mm: treewide: remove GFP_TEMPORARY allocation flag IB/mlx4: fix sprintf format warning fscache: fix fscache_objlist_show format processing lib/test_bitmap.c: use ULL suffix for 64-bit constants procfs: remove unused variable drivers/media/cec/cec-adap.c: fix build with gcc-4.4.4 idr: remove WARN_ON_ONCE() when trying to replace negative ID
| * | mm, page_owner: skip unnecessary stack_trace entriesPrakash Gupta2017-09-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The page_owner stacktrace always begin as follows: [<ffffff987bfd48f4>] save_stack+0x40/0xc8 [<ffffff987bfd4da8>] __set_page_owner+0x3c/0x6c These two entries do not provide any useful information and limits the available stacktrace depth. The page_owner stacktrace was skipping caller function from stack entries but this was missed with commit f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace") Example page_owner entry after the patch: Page allocated via order 0, mask 0x8(ffffff80085fb714) PFN 654411 type Movable Block 639 type CMA Flags 0x0(ffffffbe5c7f12c0) [<ffffff9b64989c14>] post_alloc_hook+0x70/0x80 ... [<ffffff9b651216e8>] msm_comm_try_state+0x5f8/0x14f4 [<ffffff9b6512486c>] msm_vidc_open+0x5e4/0x7d0 [<ffffff9b65113674>] msm_v4l2_open+0xa8/0x224 Link: http://lkml.kernel.org/r/1504078343-28754-2-git-send-email-guptap@codeaurora.org Fixes: f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace") Signed-off-by: Prakash Gupta <guptap@codeaurora.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * | mm: treewide: remove GFP_TEMPORARY allocation flagMichal Hocko2017-09-132-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | GFP_TEMPORARY was introduced by commit e12ba74d8ff3 ("Group short-lived and reclaimable kernel allocations") along with __GFP_RECLAIMABLE. It's primary motivation was to allow users to tell that an allocation is short lived and so the allocator can try to place such allocations close together and prevent long term fragmentation. As much as this sounds like a reasonable semantic it becomes much less clear when to use the highlevel GFP_TEMPORARY allocation flag. How long is temporary? Can the context holding that memory sleep? Can it take locks? It seems there is no good answer for those questions. The current implementation of GFP_TEMPORARY is basically GFP_KERNEL | __GFP_RECLAIMABLE which in itself is tricky because basically none of the existing caller provide a way to reclaim the allocated memory. So this is rather misleading and hard to evaluate for any benefits. I have checked some random users and none of them has added the flag with a specific justification. I suspect most of them just copied from other existing users and others just thought it might be a good idea to use without any measuring. This suggests that GFP_TEMPORARY just motivates for cargo cult usage without any reasoning. I believe that our gfp flags are quite complex already and especially those with highlevel semantic should be clearly defined to prevent from confusion and abuse. Therefore I propose dropping GFP_TEMPORARY and replace all existing users to simply use GFP_KERNEL. Please note that SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and so they will be placed properly for memory fragmentation prevention. I can see reasons we might want some gfp flag to reflect shorterm allocations but I propose starting from a clear semantic definition and only then add users with proper justification. This was been brought up before LSF this year by Matthew [1] and it turned out that GFP_TEMPORARY really doesn't have a clear semantic. It seems to be a heuristic without any measured advantage for most (if not all) its current users. The follow up discussion has revealed that opinions on what might be temporary allocation differ a lot between developers. So rather than trying to tweak existing users into a semantic which they haven't expected I propose to simply remove the flag and start from scratch if we really need a semantic for short term allocations. [1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org [akpm@linux-foundation.org: fix typo] [akpm@linux-foundation.org: coding-style fixes] [sfr@canb.auug.org.au: drm/i915: fix up] Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Neil Brown <neilb@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | sched/wait: Introduce wakeup boomark in wake_up_page_bitTim Chen2017-09-141-1/+21
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that we have added breaks in the wait queue scan and allow bookmark on scan position, we put this logic in the wake_up_page_bit function. We can have very long page wait list in large system where multiple pages share the same wait list. We break the wake up walk here to allow other cpus a chance to access the list, and not to disable the interrupts when traversing the list for too long. This reduces the interrupt and rescheduling latency, and excessive page wait queue lock hold time. [ v2: Remove bookmark_wake_function ] Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/backing-dev.c: fix an error handling path in 'cgwb_create()'Christophe JAILLET2017-09-111-2/+4
| | | | | | | | | | | | | | | | | | | | If the 'kmalloc' fails, we must go through the existing error handling path. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks") Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* | mem/memcg: cache rightmost nodeDavidlohr Bueso2017-09-081-5/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Such that we can optimize __mem_cgroup_largest_soft_limit_node(). The only overhead is the extra footprint for the cached pointer, but this should not be an issue for mem_cgroup_tree_per_node. [dave@stgolabs.net: brain fart #2] Link: http://lkml.kernel.org/r/20170731160114.GE21328@linux-80c1.suse Link: http://lkml.kernel.org/r/20170719014603.19029-17-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | lib/interval_tree: fast overlap detectionDavidlohr Bueso2017-09-084-14/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow interval trees to quickly check for overlaps to avoid unnecesary tree lookups in interval_tree_iter_first(). As of this patch, all interval tree flavors will require using a 'rb_root_cached' such that we can have the leftmost node easily available. While most users will make use of this feature, those with special functions (in addition to the generic insert, delete, search calls) will avoid using the cached option as they can do funky things with insertions -- for example, vma_interval_tree_insert_after(). [jglisse@redhat.com: fix deadlock from typo vm_lock_anon_vma()] Link: http://lkml.kernel.org/r/20170808225719.20723-1-jglisse@redhat.com Link: http://lkml.kernel.org/r/20170719014603.19029-12-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Doug Ledford <dledford@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: David Airlie <airlied@linux.ie> Cc: Jason Wang <jasowang@redhat.com> Cc: Christian Benvenuti <benve@cisco.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | treewide: make "nr_cpu_ids" unsignedAlexey Dobriyan2017-09-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | First, number of CPUs can't be negative number. Second, different signnnedness leads to suboptimal code in the following cases: 1) kmalloc(nr_cpu_ids * sizeof(X)); "int" has to be sign extended to size_t. 2) while (loff_t *pos < nr_cpu_ids) MOVSXD is 1 byte longed than the same MOV. Other cases exist as well. Basically compiler is told that nr_cpu_ids can't be negative which can't be deduced if it is "int". Code savings on allyesconfig kernel: -3KB add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370) function old new delta coretemp_cpu_online 450 512 +62 rcu_init_one 1234 1272 +38 pci_device_probe 374 399 +25 ... pgdat_reclaimable_pages 628 556 -72 select_fallback_rq 446 369 -77 task_numa_find_cpu 1923 1807 -116 Link: http://lkml.kernel.org/r/20170819114959.GA30580@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/mempolicy.c: remove BUG_ON() checks for VMA inside mpol_misplaced()Anshuman Khandual2017-09-081-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | VMA and its address bounds checks are too late in this function. They must have been verified earlier in the page fault sequence. Hence just remove them. Link: http://lkml.kernel.org/r/20170901130137.7617-1-khandual@linux.vnet.ibm.com Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> 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/swapfile.c: fix swapon frontswap_map memory leak on errorDavid Rientjes2017-09-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | Free frontswap_map if an error is encountered before enable_swap_info(). Signed-off-by: David Rientjes <rientjes@google.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: kvfree the swap cluster info if the swap file is unsatisfactoryDarrick J. Wong2017-09-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If initializing a small swap file fails because the swap file has a problem (holes, etc.) then we need to free the cluster info as part of cleanup. Unfortunately a previous patch changed the code to use kvzalloc but did not change all the vfree calls to use kvfree. Found by running generic/357 from xfstests. Link: http://lkml.kernel.org/r/20170831233515.GR3775@magnolia Fixes: 54f180d3c181 ("mm, swap: use kvzalloc to allocate some swap data structures") Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/page_alloc.c: apply gfp_allowed_mask before the first allocation attemptTetsuo Handa2017-09-081-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are by error initializing alloc_flags before gfp_allowed_mask is applied. This could cause problems after pm_restrict_gfp_mask() is called during suspend operation. Apply gfp_allowed_mask before initializing alloc_flags so that the first allocation attempt uses correct flags. Link: http://lkml.kernel.org/r/201709020016.ADJ21342.OFLJHOOSMFVtFQ@I-love.SAKURA.ne.jp Fixes: 83d4ca8148fd9092 ("mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/sparse.c: fix typo in online_mem_sectionsMichal Hocko2017-09-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | online_mem_sections() accidentally marks online only the first section in the given range. This is a typo which hasn't been noticed because I haven't tested large 2GB blocks previously. All users of pfn_to_online_page would get confused on the the rest of the pfn range in the block. All we need to fix this is to use iterator (pfn) rather than start_pfn. Link: http://lkml.kernel.org/r/20170904112210.3401-1-mhocko@kernel.org Fixes: 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes") Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.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/memory.c: fix mem_cgroup_oom_disable() call missingLaurent Dufour2017-09-081-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Seen while reading the code, in handle_mm_fault(), in the case arch_vma_access_permitted() is failing the call to mem_cgroup_oom_disable() is not made. To fix that, move the call to mem_cgroup_oom_enable() after calling arch_vma_access_permitted() as it should not have entered the memcg OOM. Link: http://lkml.kernel.org/r/1504625439-31313-1-git-send-email-ldufour@linux.vnet.ibm.com Fixes: bae473a423f6 ("mm: introduce fault_env") Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: Michal Hocko <mhocko@suse.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: memcontrol: use per-cpu stocks for socket memory unchargingRoman Gushchin2017-09-081-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We've noticed a quite noticeable performance overhead on some hosts with significant network traffic when socket memory accounting is enabled. Perf top shows that socket memory uncharging path is hot: 2.13% [kernel] [k] page_counter_cancel 1.14% [kernel] [k] __sk_mem_reduce_allocated 1.14% [kernel] [k] _raw_spin_lock 0.87% [kernel] [k] _raw_spin_lock_irqsave 0.84% [kernel] [k] tcp_ack 0.84% [kernel] [k] ixgbe_poll 0.83% < workload > 0.82% [kernel] [k] enqueue_entity 0.68% [kernel] [k] __fget 0.68% [kernel] [k] tcp_delack_timer_handler 0.67% [kernel] [k] __schedule 0.60% < workload > 0.59% [kernel] [k] __inet6_lookup_established 0.55% [kernel] [k] __switch_to 0.55% [kernel] [k] menu_select 0.54% libc-2.20.so [.] __memcpy_avx_unaligned To address this issue, the existing per-cpu stock infrastructure can be used. refill_stock() can be called from mem_cgroup_uncharge_skmem() to move charge to a per-cpu stock instead of calling atomic page_counter_uncharge(). To prevent the uncontrolled growth of per-cpu stocks, refill_stock() will explicitly drain the cached charge, if the cached value exceeds CHARGE_BATCH. This allows significantly optimize the load: 1.21% [kernel] [k] _raw_spin_lock 1.01% [kernel] [k] ixgbe_poll 0.92% [kernel] [k] _raw_spin_lock_irqsave 0.90% [kernel] [k] enqueue_entity 0.86% [kernel] [k] tcp_ack 0.85% < workload > 0.74% perf-11120.map [.] 0x000000000061bf24 0.73% [kernel] [k] __schedule 0.67% [kernel] [k] __fget 0.63% [kernel] [k] __inet6_lookup_established 0.62% [kernel] [k] menu_select 0.59% < workload > 0.59% [kernel] [k] __switch_to 0.57% libc-2.20.so [.] __memcpy_avx_unaligned Link: http://lkml.kernel.org/r/20170829100150.4580-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: fadvise: avoid fadvise for fs without backing deviceShakeel Butt2017-09-081-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The fadvise() manpage is silent on fadvise()'s effect on memory-based filesystems (shmem, hugetlbfs & ramfs) and pseudo file systems (procfs, sysfs, kernfs). The current implementaion of fadvise is mostly a noop for such filesystems except for FADV_DONTNEED which will trigger expensive remote LRU cache draining. This patch makes the noop of fadvise() on such file systems very explicit. However this change has two side effects for ramfs and one for tmpfs. First fadvise(FADV_DONTNEED) could remove the unmapped clean zero'ed pages of ramfs (allocated through read, readahead & read fault) and tmpfs (allocated through read fault). Also fadvise(FADV_WILLNEED) could create such clean zero'ed pages for ramfs. This change removes those possibilities. One of our generic libraries does fadvise(FADV_DONTNEED). Recently we observed high latency in fadvise() and noticed that the users have started using tmpfs files and the latency was due to expensive remote LRU cache draining. For normal tmpfs files (have data written on them), fadvise(FADV_DONTNEED) will always trigger the unneeded remote cache draining. Link: http://lkml.kernel.org/r/20170818011023.181465-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/zsmalloc.c: change stat type parameter to intMatthias Kaehlcke2017-09-081-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | zs_stat_inc/dec/get() uses enum zs_stat_type for the stat type, however some callers pass an enum fullness_group value. Change the type to int to reflect the actual use of the functions and get rid of 'enum-conversion' warnings Link: http://lkml.kernel.org/r/20170731175000.56538-1-mka@chromium.org Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Doug Anderson <dianders@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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>
* | mm: consider the number in local CPUs when reading NUMA statsKemi Wang2017-09-081-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To avoid deviation, the per cpu number of NUMA stats in vm_numa_stat_diff[] is included when a user *reads* the NUMA stats. Since NUMA stats does not be read by users frequently, and kernel does not need it to make a decision, it will not be a problem to make the readers more expensive. Link: http://lkml.kernel.org/r/1503568801-21305-4-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang <kemi.wang@intel.com> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Christopher Lameter <cl@linux.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Ying Huang <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: update NUMA counter threshold sizeKemi Wang2017-09-081-18/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is significant overhead in cache bouncing caused by zone counters (NUMA associated counters) update in parallel in multi-threaded page allocation (suggested by Dave Hansen). This patch updates NUMA counter threshold to a fixed size of MAX_U16 - 2, as a small threshold greatly increases the update frequency of the global counter from local per cpu counter(suggested by Ying Huang). The rationality is that these statistics counters don't affect the kernel's decision, unlike other VM counters, so it's not a problem to use a large threshold. With this patchset, we see 31.3% drop of CPU cycles(537-->369) for per single page allocation and reclaim on Jesper's page_bench03 benchmark. Benchmark provided by Jesper D Brouer(increase loop times to 10000000): https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/ bench Threshold CPU cycles Throughput(88 threads) 32 799 241760478 64 640 301628829 125 537 358906028 <==> system by default (base) 256 468 412397590 512 428 450550704 4096 399 482520943 20000 394 489009617 30000 395 488017817 65533 369(-31.3%) 521661345(+45.3%) <==> with this patchset N/A 342(-36.3%) 562900157(+56.8%) <==> disable zone_statistics Link: http://lkml.kernel.org/r/1503568801-21305-3-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang <kemi.wang@intel.com> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Suggested-by: Dave Hansen <dave.hansen@intel.com> Suggested-by: Ying Huang <ying.huang@intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Christopher Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Tim Chen <tim.c.chen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: change the call sites of numa statistics itemsKemi Wang2017-09-082-11/+160
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "Separate NUMA statistics from zone statistics", v2. Each page allocation updates a set of per-zone statistics with a call to zone_statistics(). As discussed in 2017 MM summit, these are a substantial source of overhead in the page allocator and are very rarely consumed. This significant overhead in cache bouncing caused by zone counters (NUMA associated counters) update in parallel in multi-threaded page allocation (pointed out by Dave Hansen). A link to the MM summit slides: http://people.netfilter.org/hawk/presentations/MM-summit2017/MM-summit2017-JesperBrouer.pdf To mitigate this overhead, this patchset separates NUMA statistics from zone statistics framework, and update NUMA counter threshold to a fixed size of MAX_U16 - 2, as a small threshold greatly increases the update frequency of the global counter from local per cpu counter (suggested by Ying Huang). The rationality is that these statistics counters don't need to be read often, unlike other VM counters, so it's not a problem to use a large threshold and make readers more expensive. With this patchset, we see 31.3% drop of CPU cycles(537-->369, see below) for per single page allocation and reclaim on Jesper's page_bench03 benchmark. Meanwhile, this patchset keeps the same style of virtual memory statistics with little end-user-visible effects (only move the numa stats to show behind zone page stats, see the first patch for details). I did an experiment of single page allocation and reclaim concurrently using Jesper's page_bench03 benchmark on a 2-Socket Broadwell-based server (88 processors with 126G memory) with different size of threshold of pcp counter. Benchmark provided by Jesper D Brouer(increase loop times to 10000000): https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench Threshold CPU cycles Throughput(88 threads) 32 799 241760478 64 640 301628829 125 537 358906028 <==> system by default 256 468 412397590 512 428 450550704 4096 399 482520943 20000 394 489009617 30000 395 488017817 65533 369(-31.3%) 521661345(+45.3%) <==> with this patchset N/A 342(-36.3%) 562900157(+56.8%) <==> disable zone_statistics This patch (of 3): In this patch, NUMA statistics is separated from zone statistics framework, all the call sites of NUMA stats are changed to use numa-stats-specific functions, it does not have any functionality change except that the number of NUMA stats is shown behind zone page stats when users *read* the zone info. E.g. cat /proc/zoneinfo ***Base*** ***With this patch*** nr_free_pages 3976 nr_free_pages 3976 nr_zone_inactive_anon 0 nr_zone_inactive_anon 0 nr_zone_active_anon 0 nr_zone_active_anon 0 nr_zone_inactive_file 0 nr_zone_inactive_file 0 nr_zone_active_file 0 nr_zone_active_file 0 nr_zone_unevictable 0 nr_zone_unevictable 0 nr_zone_write_pending 0 nr_zone_write_pending 0 nr_mlock 0 nr_mlock 0 nr_page_table_pages 0 nr_page_table_pages 0 nr_kernel_stack 0 nr_kernel_stack 0 nr_bounce 0 nr_bounce 0 nr_zspages 0 nr_zspages 0 numa_hit 0 *nr_free_cma 0* numa_miss 0 numa_hit 0 numa_foreign 0 numa_miss 0 numa_interleave 0 numa_foreign 0 numa_local 0 numa_interleave 0 numa_other 0 numa_local 0 *nr_free_cma 0* numa_other 0 ... ... vm stats threshold: 10 vm stats threshold: 10 ... ... The next patch updates the numa stats counter size and threshold. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1503568801-21305-2-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang <kemi.wang@intel.com> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christopher Lameter <cl@linux.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Ying Huang <ying.huang@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/memory.c: remove reduntant check for write accessAnshuman Khandual2017-09-081-3/+2
| | | | | | | | | | | | | | | | | | | | | | Flags argument has been copied into vmf.flags and it is not changed in between. Hence a single write access check can be used for both PUD and PMD. Link: http://lkml.kernel.org/r/20170823082839.1812-1-khandual@linux.vnet.ibm.com Signed-off-by: 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>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-20 03:50:46 +0000