- 15 Dec, 2020 40 commits
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Alex Shi authored
Currently lru_lock still guards both lru list and page's lru bit, that's ok. but if we want to use specific lruvec lock on the page, we need to pin down the page's lruvec/memcg during locking. Just taking lruvec lock first may be undermined by the page's memcg charge/migration. To fix this problem, we will clear the lru bit out of locking and use it as pin down action to block the page isolation in memcg changing. So now a standard steps of page isolation is following: 1, get_page(); #pin the page avoid to be free 2, TestClearPageLRU(); #block other isolation like memcg change 3, spin_lock on lru_lock; #serialize lru list access 4, delete page from lru list; This patch start with the first part: TestClearPageLRU, which combines PageLRU check and ClearPageLRU into a macro func TestClearPageLRU. This function will be used as page isolation precondition to prevent other isolations some where else. Then there are may !PageLRU page on lru list, need to remove BUG() checking accordingly. There 2 rules for lru bit now: 1, the lru bit still indicate if a page on lru list, just in some temporary moment(isolating), the page may have no lru bit when it's on lru list. but the page still must be on lru list when the lru bit set. 2, have to remove lru bit before delete it from lru list. As Andrew Morton mentioned this change would dirty cacheline for a page which isn't on the LRU. But the loss would be acceptable in Rong Chen <rong.a.chen@intel.com> report: https://lore.kernel.org/lkml/20200304090301.GB5972@shao2-debian/ Link: https://lkml.kernel.org/r/1604566549-62481-15-git-send-email-alex.shi@linux.alibaba.comSuggested-by:
Johannes Weiner <hannes@cmpxchg.org> Signed-off-by:
Alex Shi <alex.shi@linux.alibaba.com> Acked-by:
Hugh Dickins <hughd@google.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Alex Shi authored
__munlock_isolate_lru_page() only has one caller, remove it to clean up and simplify code. Link: https://lkml.kernel.org/r/1604566549-62481-14-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
In the func munlock_vma_page, comments mentained lru_lock needed for serialization with split_huge_pages. But the page must be PageLocked as well as pages in split_huge_page series funcs. Thus the PageLocked is enough to serialize both funcs. Further more, Hugh Dickins pointed: before splitting in split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes which protect the page from munlock. Thus, no needs to guard __split_huge_page_tail for mlock clean, just keep the lru_lock there for isolation purpose. LKP found a preempt issue on __mod_zone_page_state which need change to mod_zone_page_state. Thanks! Link: https://lkml.kernel.org/r/1604566549-62481-13-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
Isolated page shouldn't be recharged by memcg since the memcg migration isn't possible at the time. All pages were isolated from the same lruvec (and isolation inhibits memcg migration). So remove unnecessary regetting. Thanks to Alexander Duyck for pointing this out. Link: https://lkml.kernel.org/r/1604566549-62481-12-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
We have to move lru_lock into lru_note_cost, since it cycle up on memcg tree, for future per lruvec lru_lock replace. It's a bit ugly and may cost a bit more locking, but benefit from multiple memcg locking could cover the lost. Link: https://lkml.kernel.org/r/1604566549-62481-11-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
Fold the PGROTATED event collection into pagevec_move_tail_fn call back func like other funcs does in pagevec_lru_move_fn. Thus we could save func call pagevec_move_tail(). Now all usage of pagevec_lru_move_fn are same and no needs of its 3rd parameter. It's just simply the calling. No functional change. [lkp@intel.com: found a build issue in the original patch, thanks] Link: https://lkml.kernel.org/r/1604566549-62481-10-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
Add a debug checking in lock_page_memcg, then we could get alarm if anything wrong here. Link: https://lkml.kernel.org/r/1604566549-62481-9-git-send-email-alex.shi@linux.alibaba.comSuggested-by:
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Hugh Dickins authored
It is necessary for page_idle_get_page() to recheck PageLRU() after get_page_unless_zero(), but holding lru_lock around that serves no useful purpose, and adds to lru_lock contention: delete it. See https://lore.kernel.org/lkml/20150504031722.GA2768@blaptop for the discussion that led to lru_lock there; but __page_set_anon_rmap() now uses WRITE_ONCE(), and I see no other risk in page_idle_clear_pte_refs() using rmap_walk() (beyond the risk of racing PageAnon->PageKsm, mostly but not entirely prevented by page_count() check in ksm.c's write_protect_page(): that risk being shared with page_referenced() and not helped by lru_lock). Link: https://lkml.kernel.org/r/1604566549-62481-8-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
"Huang, Ying" <ying.huang@intel.com> Acked-by:
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Alex Shi authored
Hugh Dickins and Minchan Kim observed a long time issue which discussed here, but actully the mentioned fix in https://lore.kernel.org/lkml/20150504031722.GA2768@blaptop/ was missed. The store reordering may cause problem in the scenario: CPU 0 CPU1 do_anonymous_page page_add_new_anon_rmap() page->mapping = anon_vma + PAGE_MAPPING_ANON lru_cache_add_inactive_or_unevictable() spin_lock(lruvec->lock) SetPageLRU() spin_unlock(lruvec->lock) /* idletacking judged it as LRU * page so pass the page in * page_idle_clear_pte_refs */ page_idle_clear_pte_refs rmap_walk if PageAnon(page) Johannes give detailed examples how the store reordering could cause trouble: "The concern is the SetPageLRU may get reorder before 'page->mapping' setting, That would make CPU 1 will observe at page->mapping after observing PageLRU set on the page. 1. anon_vma + PAGE_MAPPING_ANON That's the in-order scenario and is fine. 2. NULL That's possible if the page->mapping store gets reordered to occur after SetPageLRU. That's fine too because we check for it. 3. anon_vma without the PAGE_MAPPING_ANON bit That would be a problem and could lead to all kinds of undesirable behavior including crashes and data corruption. Is it possible? AFAICT the compiler is allowed to tear the store to page->mapping and I don't see anything that would prevent it. That said, I also don't see how the reader testing PageLRU under the lru_lock would prevent that in the first place. AFAICT we need that WRITE_ONCE() around the page->mapping assignment." [alex.shi@linux.alibaba.com: updated for comments change from Johannes] Link: https://lkml.kernel.org/r/e66ef2e5-c74c-6498-e8b3-56c37b9d2d15@linux.alibaba.com Link: https://lkml.kernel.org/r/1604566549-62481-7-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
We don't have to add a freeable page into lru and then remove from it. This change saves a couple of actions and makes the moving more clear. The SetPageLRU needs to be kept before put_page_testzero for list integrity, otherwise: #0 move_pages_to_lru #1 release_pages if !put_page_testzero if (put_page_testzero()) !PageLRU //skip lru_lock SetPageLRU() list_add(&page->lru,) list_add(&page->lru,) [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/1604566549-62481-6-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: -
Alex Shi authored
lru_lock and page cache xa_lock have no obvious reason to be taken one way round or the other: until now, lru_lock has been taken before page cache xa_lock, when splitting a THP; but nothing else takes them together. Reverse that ordering: let's narrow the lru locking - but leave local_irq_disable to block interrupts throughout, like before. Hugh Dickins point: split_huge_page_to_list() was already silly, to be using the _irqsave variant: it's just been taking sleeping locks, so would already be broken if entered with interrupts enabled. So we can save passing flags argument down to __split_huge_page(). Why change the lock ordering here? That was hard to decide. One reason: when this series reaches per-memcg lru locking, it relies on the THP's memcg to be stable when taking the lru_lock: that is now done after the THP's refcount has been frozen, which ensures page memcg cannot change. Another reason: previously, lock_page_memcg()'s move_lock was presumed to nest inside lru_lock; but now lru_lock must nest inside (page cache lock inside) move_lock, so it becomes possible to use lock_page_memcg() to stabilize page memcg before taking its lru_lock. That is not the mechanism used in this series, but it is an option we want to keep open. [hughd@google.com: rewrite commit log] Link: https://lkml.kernel.org/r/1604566549-62481-5-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by:
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Alex Shi authored
Simplify lru_add_page_tail(), there are actually only two cases possible: split_huge_page_to_list(), with list supplied and head isolated from lru by its caller; or split_huge_page(), with NULL list and head on lru - because when head is racily isolated from lru, the isolator's reference will stop the split from getting any further than its page_ref_freeze(). So decide between the two cases by "list", but add VM_WARN_ON()s to verify that they match our lru expectations. [Hugh Dickins: rewrite commit log] Link: https://lkml.kernel.org/r/1604566549-62481-4-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Alex Shi authored
Since the first parameter is only used by head page, it's better to make it explicit. Link: https://lkml.kernel.org/r/1604566549-62481-3-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by:
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Alex Shi authored
Patch series "per memcg lru lock", v21. This patchset includes 3 parts: 1) some code cleanup and minimum optimization as preparation 2) use TestCleanPageLRU as page isolation's precondition 3) replace per node lru_lock with per memcg per node lru_lock Current lru_lock is one for each of node, pgdat->lru_lock, that guard for lru lists, but now we had moved the lru lists into memcg for long time. Still using per node lru_lock is clearly unscalable, pages on each of memcgs have to compete each others for a whole lru_lock. This patchset try to use per lruvec/memcg lru_lock to repleace per node lru lock to guard lru lists, make it scalable for memcgs and get performance gain. Currently lru_lock still guards both lru list and page's lru bit, that's ok. but if we want to use specific lruvec lock on the page, we need to pin down the page's lruvec/memcg during locking. Just taking lruvec lock first may be undermined by the page's memcg charge/migration. To fix this problem, we could take out the page's lru bit clear and use it as pin down action to block the memcg changes. That's the reason for new atomic func TestClearPageLRU. So now isolating a page need both actions: TestClearPageLRU and hold the lru_lock. The typical usage of this is isolate_migratepages_block() in compaction.c we have to take lru bit before lru lock, that serialized the page isolation in memcg page charge/migration which will change page's lruvec and new lru_lock in it. The above solution suggested by Johannes Weiner, and based on his new memcg charge path, then have this patchset. (Hugh Dickins tested and contributed much code from compaction fix to general code polish, thanks a lot!). Daniel Jordan's testing show 62% improvement on modified readtwice case on his 2P * 10 core * 2 HT broadwell box on v18, which has no much different with this v20. https://lore.kernel.org/lkml/20200915165807.kpp7uhiw7l3loofu@ca-dmjordan1.us.oracle.com/ Thanks to Hugh Dickins and Konstantin Khlebnikov, they both brought this idea 8 years ago, and others who gave comments as well: Daniel Jordan, Mel Gorman, Shakeel Butt, Matthew Wilcox, Alexander Duyck etc. Thanks for Testing support from Intel 0day and Rong Chen, Fengguang Wu, and Yun Wang. Hugh Dickins also shared his kbuild-swap case. This patch (of 19): lru_add_page_tail() is only used in huge_memory.c, defining it in other file with a CONFIG_TRANSPARENT_HUGEPAGE macro restrict just looks weird. Let's move it THP. And make it static as Hugh Dickins suggested. Link: https://lkml.kernel.org/r/1604566549-62481-1-git-send-email-alex.shi@linux.alibaba.com Link: https://lkml.kernel.org/r/1604566549-62481-2-git-send-email-alex.shi@linux.alibaba.comSigned-off-by:
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Linus Torvalds authored
Merge misc updates from Andrew Morton: - a few random little subsystems - almost all of the MM patches which are staged ahead of linux-next material. I'll trickle to post-linux-next work in as the dependents get merged up. Subsystems affected by this patch series: kthread, kbuild, ide, ntfs, ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache, gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation, kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction, oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc, uaccess, zram, and cleanups). * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (200 commits) mm: cleanup kstrto*() usage mm: fix fall-through warnings for Clang mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at mm: shmem: convert shmem_enabled_show to use sysfs_emit_at mm:backing-dev: use sysfs_emit in macro defining functions mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening mm: use sysfs_emit for struct kobject * uses mm: fix kernel-doc markups zram: break the strict dependency from lzo zram: add stat to gather incompressible pages since zram set up zram: support page writeback mm/process_vm_access: remove redundant initialization of iov_r mm/zsmalloc.c: rework the list_add code in insert_zspage() mm/zswap: move to use crypto_acomp API for hardware acceleration mm/zswap: fix passing zero to 'PTR_ERR' warning mm/zswap: make struct kernel_param_ops definitions const userfaultfd/selftests: hint the test runner on required privilege userfaultfd/selftests: fix retval check for userfaultfd_open() userfaultfd/selftests: always dump something in modes userfaultfd: selftests: make __{s,u}64 format specifiers portable ... -
Alexey Dobriyan authored
Range checks can folded into proper conversion function. kstrto*() exist for all arithmetic types. Link: https://lkml.kernel.org/r/20201122123759.GC92364@localhost.localdomainSigned-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
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Gustavo A. R. Silva authored
In preparation to enable -Wimplicit-fallthrough for Clang, fix a couple of warnings by explicitly adding a break statement instead of just letting the code fall through to the next, and by adding a fallthrough pseudo-keyword in places where the code is intended to fall through. Link: https://github.com/KSPP/linux/issues/115 Link: https://lkml.kernel.org/r/f5756988b8842a3f10008fbc5b0a654f828920a9.1605896059.git.gustavoars@kernel.orgSigned-off-by:
Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by:
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Joe Perches authored
Convert the unbounded uses of sprintf to sysfs_emit. A few conversions may now not end in a newline if the output buffer is overflowed. Link: https://lkml.kernel.org/r/0c90a90f466167f8c37de4b737553cf49c4a277f.1605376435.git.joe@perches.comSigned-off-by:
Joe Perches <joe@perches.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by:
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Joe Perches authored
Update the function to use sysfs_emit_at while neatening the uses of sprintf and overwriting the last space char with a newline to avoid possible output buffer overflow. Miscellanea: - in shmem_enabled_show, the removal of the indirected use of fmt allows __printf verification Link: https://lkml.kernel.org/r/b612a93825e5ea330cb68d2e8b516e9687a06cc6.1605376435.git.joe@perches.comSigned-off-by:
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Joe Perches authored
The cocci script used in commit bdacbb8d04f ("mm: Use sysfs_emit for struct kobject * uses") does not convert the name##_show macro because the macro uses concatenation via ##. Convert it by hand. Link: https://lkml.kernel.org/r/45ec6cfc177d743f9c0ebaf35e43969dce43af42.1605376435.git.joe@perches.comSigned-off-by: -
Joe Perches authored
Convert the only use of sprintf with struct kobject * that the cocci script could not convert. Miscellanea: - Neaten the uses of a constant string with sysfs_emit to use a const char * to reduce overall object size Link: https://lkml.kernel.org/r/7df6be66bbd68e1a0bca9d35aca1341dbf94d2a7.1605376435.git.joe@perches.comSigned-off-by:
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Joe Perches authored
Patch series "mm: Convert sysfs sprintf family to sysfs_emit", v2. Use the new sysfs_emit family and not the sprintf family. This patch (of 5): Use the sysfs_emit function instead of the sprintf family. Done with cocci script as in commit 3c6bff3c ("RDMA: Convert sysfs kobject * show functions to use sysfs_emit()") Link: https://lkml.kernel.org/r/cover.1605376435.git.joe@perches.com Link: https://lkml.kernel.org/r/9c249215bad6df616ba0410ad980042694970c1b.1605376435.git.joe@perches.comSigned-off-by:
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Mauro Carvalho Chehab authored
Kernel-doc markups should use this format: identifier - description Fix some issues on mm files: 1) The definition for get_user_pages_locked() doesn't follow it. Also, it expects a short descrpition at the header, followed by a long one, after the parameters. Fix it. 2) Kernel-doc requires that a kernel-doc markup to be immediately below the function prototype, as otherwise it will rename it. So, move get_pfnblock_flags_mask() description to the right place. 3) Make invalidate_mapping_pagevec() to also follow the expected kernel-doc format. While here, fix a few minor English syntax issues, as suggested by Matthew: will used -> will be used similar with -> similar to Link: https://lkml.kernel.org/r/80e85dddc92d333bc2159ee8a2294921612e8745.1605521731.git.mchehab+huawei@kernel.orgSigned-off-by:Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Suggested-by: Mattew Wilcox <willy@infradead.org> [English fixes] Signed-off-by:
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Rui Salvaterra authored
From the beginning, the zram block device always enabled CRYPTO_LZO, since lzo-rle is hardcoded as the fallback compression algorithm. As a consequence, on systems where another compression algorithm is chosen (e.g. CRYPTO_ZSTD), the lzo kernel module becomes unused, while still having to be built/loaded. This patch removes the hardcoded lzo-rle dependency and allows the user to select the default compression algorithm for zram at build time. The previous behaviour is kept, as the default algorithm is still lzo-rle. Link: https://lkml.kernel.org/r/20201207121245.50529-1-rsalvaterra@gmail.comSigned-off-by:
Rui Salvaterra <rsalvaterra@gmail.com> Suggested-by:
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Suggested-by:
Minchan Kim <minchan@kernel.org> Acked-by:
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Minchan Kim authored
Currently, zram supports the stat via /sys/block/zram/mm_stat to represent how many of incompressible pages are stored at the moment but it couldn't show how many times incompressible pages were wrote down since zram set up. It's also good indication to see how zram is effective in the system. Link: https://lkml.kernel.org/r/20201130201907.1284910-1-minchan@kernel.orgSigned-off-by:
Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by:
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Minchan Kim authored
There is demand to writeback specific process pages to backing store instead of all idles pages in the system due to storage wear out concerns and to launching latency of apps which are most of the time idle but are critical for resume latency. This patch extends the writeback knob to support a specific page writeback. Link: https://lkml.kernel.org/r/20201020190506.3758660-1-minchan@kernel.orgSigned-off-by:
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Colin Ian King authored
The pointer iov_r is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and can be removed. Link: https://lkml.kernel.org/r/20201102120614.694917-1-colin.king@canonical.comSigned-off-by:
Colin Ian King <colin.king@canonical.com> Reviewed-by:
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Miaohe Lin authored
Rework the list_add code to make it more readable and simple. Link: https://lkml.kernel.org/r/20201015130107.65195-1-linmiaohe@huawei.comSigned-off-by:
Miaohe Lin <linmiaohe@huawei.com> Acked-by:
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Barry Song authored
Right now, all new ZIP drivers are adapted to crypto_acomp APIs rather than legacy crypto_comp APIs. Tradiontal ZIP drivers like lz4,lzo etc have been also wrapped into acomp via scomp backend. But zswap.c is still using the old APIs. That means zswap won't be able to work on any new ZIP drivers in kernel. This patch moves to use cryto_acomp APIs to fix the disconnected bridge between new ZIP drivers and zswap. It is probably the first real user to use acomp but perhaps not a good example to demonstrate how multiple acomp requests can be executed in parallel in one acomp instance. frontswap is doing page load and store page by page synchronously. swap_writepage() depends on the completion of frontswap_store() to decide if it should call __swap_writepage() to swap to disk. However this patch creates multiple acomp instances, so multiple threads running on multiple different cpus can actually do (de)compression parallelly, leveraging the power of multiple ZIP hardware queues. This is also consistent with frontswap's page management model. The old zswap code uses atomic context and avoids the race conditions while shared resources like zswap_dstmem are accessed. Here since acomp can sleep, per-cpu mutex is used to replace preemption-disable. While it is possible to make mm/page_io.c and mm/frontswap.c support async (de)compression in some way, the entire design requires careful thinking and performance evaluation. For the first step, the base with fixed connection between ZIP drivers and zswap should be built. Link: https://lkml.kernel.org/r/20201107065332.26992-1-song.bao.hua@hisilicon.comSigned-off-by:
Barry Song <song.bao.hua@hisilicon.com> Acked-by:
Vitaly Wool <vitalywool@gmail.com> Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David S. Miller <davem@davemloft.net> Cc: Mahipal Challa <mahipalreddy2006@gmail.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Zhou Wang <wangzhou1@hisilicon.com> Cc: Colin Ian King <colin.king@canonical.com> Signed-off-by:
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YueHaibing authored
Fix smatch warning: mm/zswap.c:425 zswap_cpu_comp_prepare() warn: passing zero to 'PTR_ERR' crypto_alloc_comp() never return NULL, use IS_ERR instead of IS_ERR_OR_NULL to fix this. Link: https://lkml.kernel.org/r/20201031055615.28080-1-yuehaibing@huawei.com Fixes: f1c54846 ("zswap: dynamic pool creation") Signed-off-by:
YueHaibing <yuehaibing@huawei.com> Reviewed-by:
David Hildenbrand <david@redhat.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Vitaly Wool <vitaly.wool@konsulko.com> Signed-off-by:
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Joe Perches authored
These should be const, so make it so. Link: https://lkml.kernel.org/r/1791535ee0b00f4a5c68cc4a8adada06593ad8f1.1601770305.git.joe@perches.comSigned-off-by:
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Peter Xu authored
Now userfaultfd test program requires either root or ptrace privilege due to the signal/event tests. When UFFDIO_API failed, hint the test runner about this fact verbosely. Link: https://lkml.kernel.org/r/20201208024709.7701-4-peterx@redhat.comSigned-off-by:
Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by:
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Peter Xu authored
userfaultfd_open() returns 1 for errors rather than negatives. Fix it on all the callers so when UFFDIO_API failed the test will bail out. Link: https://lkml.kernel.org/r/20201208024709.7701-3-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Patch series "userfaultfd: selftests: Small fixes". Some very trivial fixes that I kept locally to userfaultfd selftest program. This patch (of 3): BOUNCE_POLL is a special bit that if cleared it means "READ" instead. Dump that too otherwise we'll see tests with empty modes. Link: https://lkml.kernel.org/r/20201208024709.7701-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20201208024709.7701-2-peterx@redhat.comSigned-off-by:
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Axel Rasmussen authored
On certain platforms (powerpcle is the one on which I ran into this), "%Ld" and "%Lu" are unsuitable for printing __s64 and __u64, respectively, resulting in build warnings. Cast to {u,}int64_t, and use the PRI{d,u}64 macros defined in inttypes.h to print them. This ought to be portable to all platforms. Splitting this off into a separate macro lets us remove some lines, and get rid of some (I would argue) stylistically odd cases where we joined printf() and exit() into a single statement with a ,. Finally, this also fixes a "missing braces around initializer" warning when we initialize prms in wp_range(). [axelrasmussen@google.com: v2] Link: https://lkml.kernel.org/r/20201203180244.1811601-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20201202211542.1121189-1-axelrasmussen@google.comSigned-off-by:Axel Rasmussen <axelrasmussen@google.com> Acked-by:
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Lokesh Gidra authored
With this change, when the knob is set to 0, it allows unprivileged users to call userfaultfd, like when it is set to 1, but with the restriction that page faults from only user-mode can be handled. In this mode, an unprivileged user (without SYS_CAP_PTRACE capability) must pass UFFD_USER_MODE_ONLY to userfaultd or the API will fail with EPERM. This enables administrators to reduce the likelihood that an attacker with access to userfaultfd can delay faulting kernel code to widen timing windows for other exploits. The default value of this knob is changed to 0. This is required for correct functioning of pipe mutex. However, this will fail postcopy live migration, which will be unnoticeable to the VM guests. To avoid this, set 'vm.userfault = 1' in /sys/sysctl.conf. The main reason this change is desirable as in the short term is that the Android userland will behave as with the sysctl set to zero. So without this commit, any Linux binary using userfaultfd to manage its memory would behave differently if run within the Android userland. For more details, refer to Andrea's reply [1]. [1] https://lore.kernel.org/lkml/20200904033438.GI9411@redhat.com/ Link: https://lkml.kernel.org/r/20201120030411.2690816-3-lokeshgidra@google.comSigned-off-by:
Lokesh Gidra <lokeshgidra@google.com> Reviewed-by:
Andrea Arcangeli <aarcange@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Peter Xu <peterx@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Daniel Colascione <dancol@dancol.org> Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: <calin@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Shaohua Li <shli@fb.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Nitin Gupta <nigupta@nvidia.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Daniel Colascione <dancol@google.com> Signed-off-by:
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Lokesh Gidra authored
Patch series "Control over userfaultfd kernel-fault handling", v6. This patch series is split from [1]. The other series enables SELinux support for userfaultfd file descriptors so that its creation and movement can be controlled. It has been demonstrated on various occasions that suspending kernel code execution for an arbitrary amount of time at any access to userspace memory (copy_from_user()/copy_to_user()/...) can be exploited to change the intended behavior of the kernel. For instance, handling page faults in kernel-mode using userfaultfd has been exploited in [2, 3]. Likewise, FUSE, which is similar to userfaultfd in this respect, has been exploited in [4, 5] for similar outcome. This small patch series adds a new flag to userfaultfd(2) that allows callers to give up the ability to handle kernel-mode faults with the resulting UFFD file object. It then adds a 'user-mode only' option to the unprivileged_userfaultfd sysctl knob to require unprivileged callers to use this new flag. The purpose of this new interface is to decrease the chance of an unprivileged userfaultfd user taking advantage of userfaultfd to enhance security vulnerabilities by lengthening the race window in kernel code. [1] https://lore.kernel.org/lkml/20200211225547.235083-1-dancol@google.com/ [2] https://duasynt.com/blog/linux-kernel-heap-spray [3] https://duasynt.com/blog/cve-2016-6187-heap-off-by-one-exploit [4] https://googleprojectzero.blogspot.com/2016/06/exploiting-recursion-in-linux-kernel_20.html [5] https://bugs.chromium.org/p/project-zero/issues/detail?id=808 This patch (of 2): userfaultfd handles page faults from both user and kernel code. Add a new UFFD_USER_MODE_ONLY flag for userfaultfd(2) that makes the resulting userfaultfd object refuse to handle faults from kernel mode, treating these faults as if SIGBUS were always raised, causing the kernel code to fail with EFAULT. A future patch adds a knob allowing administrators to give some processes the ability to create userfaultfd file objects only if they pass UFFD_USER_MODE_ONLY, reducing the likelihood that these processes will exploit userfaultfd's ability to delay kernel page faults to open timing windows for future exploits. Link: https://lkml.kernel.org/r/20201120030411.2690816-1-lokeshgidra@google.com Link: https://lkml.kernel.org/r/20201120030411.2690816-2-lokeshgidra@google.comSigned-off-by:
Daniel Colascione <dancol@google.com> Signed-off-by:
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Vlastimil Babka authored
CONFIG_PAGE_POISONING_ZERO uses the zero pattern instead of 0xAA. It was introduced by commit 1414c7f4 ("mm/page_poisoning.c: allow for zero poisoning"), noting that using zeroes retains the benefit of sanitizing content of freed pages, with the benefit of not having to zero them again on alloc, and the downside of making some forms of corruption (stray writes of NULLs) harder to detect than with the 0xAA pattern. Together with CONFIG_PAGE_POISONING_NO_SANITY it made possible to sanitize the contents on free without checking it back on alloc. These days we have the init_on_free() option to achieve sanitization with zeroes and to save clearing on alloc (and without checking on alloc). Arguably if someone does choose to check the poison for corruption on alloc, the savings of not clearing the page are secondary, and it makes sense to always use the 0xAA poison pattern. Thus, remove the CONFIG_PAGE_POISONING_ZERO option for being redundant. Link: https://lkml.kernel.org/r/20201113104033.22907-6-vbabka@suse.czSigned-off-by:
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Vlastimil Babka authored
CONFIG_PAGE_POISONING_NO_SANITY skips the check on page alloc whether the poison pattern was corrupted, suggesting a use-after-free. The motivation to introduce it in commit 8823b1db ("mm/page_poison.c: enable PAGE_POISONING as a separate option") was to simply sanitize freed pages, optimally together with CONFIG_PAGE_POISONING_ZERO. These days we have an init_on_free=1 boot option, which makes this use case of page poisoning redundant. For sanitizing, writing zeroes is sufficient, there is pretty much no benefit from writing the 0xAA poison pattern to freed pages, without checking it back on alloc. Thus, remove this option and suggest init_on_free instead in the main config's help. Link: https://lkml.kernel.org/r/20201113104033.22907-5-vbabka@suse.czSigned-off-by:
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Vlastimil Babka authored
Page poisoning used to be incompatible with hibernation, as the state of poisoned pages was lost after resume, thus enabling CONFIG_HIBERNATION forces CONFIG_PAGE_POISONING_NO_SANITY. For the same reason, the poisoning with zeroes variant CONFIG_PAGE_POISONING_ZERO used to disable hibernation. The latter restriction was removed by commit 1ad1410f ("PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO") and similarly for init_on_free by commit 18451f9f ("PM: hibernate: fix crashes with init_on_free=1") by making sure free pages are cleared after resume. We can use the same mechanism to instead poison free pages with PAGE_POISON after resume. This covers both zero and 0xAA patterns. Thus we can remove the Kconfig restriction that disables page poison sanity checking when hibernation is enabled. Link: https://lkml.kernel.org/r/20201113104033.22907-4-vbabka@suse.czSigned-off-by:
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