user/sven/linux.git/mm, branch v5.16

mm: vmscan: reduce throttling due to a failure to make progress -fix

2021-12-31T21:12:55Z

Hugh Dickins reported the following My tmpfs swapping load (tweaked to use huge pages more heavily than in real life) is far from being a realistic load: but it was notably slowed down by your throttling mods in 5.16-rc, and this patch makes it well again - thanks. But: it very quickly hit NULL pointer until I changed that last line to if (first_pgdat) consider_reclaim_throttle(first_pgdat, sc); The likely issue is that huge pages are a major component of the test workload. When this is the case, first_pgdat may never get set if compaction is ready to continue due to this check if (IS_ENABLED(CONFIG_COMPACTION) && sc->order > PAGE_ALLOC_COSTLY_ORDER && compaction_ready(zone, sc)) { sc->compaction_ready = true; continue; } If this was true for every zone in the zonelist, first_pgdat would never get set resulting in a NULL pointer exception. Link: https://lkml.kernel.org/r/20211209095453.GM3366@techsingularity.net Fixes: 1b4e3f26f9f75 ("mm: vmscan: Reduce throttling due to a failure to make progress") Signed-off-by: Mel Gorman Reported-by: Hugh Dickins Cc: Michal Hocko Cc: Vlastimil Babka Cc: Rik van Riel Cc: Mike Galbraith Cc: Darrick J. Wong Cc: Shakeel Butt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: vmscan: Reduce throttling due to a failure to make progress

2021-12-31T19:17:07Z

Mike Galbraith, Alexey Avramov and Darrick Wong all reported similar problems due to reclaim throttling for excessive lengths of time. In Alexey's case, a memory hog that should go OOM quickly stalls for several minutes before stalling. In Mike and Darrick's cases, a small memcg environment stalled excessively even though the system had enough memory overall. Commit 69392a403f49 ("mm/vmscan: throttle reclaim when no progress is being made") introduced the problem although commit a19594ca4a8b ("mm/vmscan: increase the timeout if page reclaim is not making progress") made it worse. Systems at or near an OOM state that cannot be recovered must reach OOM quickly and memcg should kill tasks if a memcg is near OOM. To address this, only stall for the first zone in the zonelist, reduce the timeout to 1 tick for VMSCAN_THROTTLE_NOPROGRESS and only stall if the scan control nr_reclaimed is 0, kswapd is still active and there were excessive pages pending for writeback. If kswapd has stopped reclaiming due to excessive failures, do not stall at all so that OOM triggers relatively quickly. Similarly, if an LRU is simply congested, only lightly throttle similar to NOPROGRESS. Alexey's original case was the most straight forward for i in {1..3}; do tail /dev/zero; done On vanilla 5.16-rc1, this test stalled heavily, after the patch the test completes in a few seconds similar to 5.15. Alexey's second test case added watching a youtube video while tail runs 10 times. On 5.15, playback only jitters slightly, 5.16-rc1 stalls a lot with lots of frames missing and numerous audio glitches. With this patch applies, the video plays similarly to 5.15. [lkp@intel.com: Fix W=1 build warning] Link: https://lore.kernel.org/r/99e779783d6c7fce96448a3402061b9dc1b3b602.camel@gmx.de Link: https://lore.kernel.org/r/20211124011954.7cab9bb4@mail.inbox.lv Link: https://lore.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net Link: https://lore.kernel.org/r/20211202150614.22440-1-mgorman@techsingularity.net Link: https://linux-regtracking.leemhuis.info/regzbot/regression/20211124011954.7cab9bb4@mail.inbox.lv/ Reported-and-tested-by: Alexey Avramov Reported-and-tested-by: Mike Galbraith Reported-and-tested-by: Darrick J. Wong Reported-by: kernel test robot Acked-by: Hugh Dickins Tracked-by: Thorsten Leemhuis Fixes: 69392a403f49 ("mm/vmscan: throttle reclaim when no progress is being made") Signed-off-by: Mel Gorman Signed-off-by: Linus Torvalds

mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'

2021-12-31T17:20:12Z

DAMON debugfs interface increases the reference counts of 'struct pid's for targets from the 'target_ids' file write callback ('dbgfs_target_ids_write()'), but decreases the counts only in DAMON monitoring termination callback ('dbgfs_before_terminate()'). Therefore, when 'target_ids' file is repeatedly written without DAMON monitoring start/termination, the reference count is not decreased and therefore memory for the 'struct pid' cannot be freed. This commit fixes this issue by decreasing the reference counts when 'target_ids' is written. Link: https://lkml.kernel.org/r/20211229124029.23348-1-sj@kernel.org Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") Signed-off-by: SeongJae Park Cc: [5.15+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()

2021-12-25T20:20:56Z

Hulk Robot reported a panic in put_page_testzero() when testing madvise() with MADV_SOFT_OFFLINE. The BUG() is triggered when retrying get_any_page(). This is because we keep MF_COUNT_INCREASED flag in second try but the refcnt is not increased. page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:737! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 5 PID: 2135 Comm: sshd Tainted: G B 5.16.0-rc6-dirty #373 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: release_pages+0x53f/0x840 Call Trace: free_pages_and_swap_cache+0x64/0x80 tlb_flush_mmu+0x6f/0x220 unmap_page_range+0xe6c/0x12c0 unmap_single_vma+0x90/0x170 unmap_vmas+0xc4/0x180 exit_mmap+0xde/0x3a0 mmput+0xa3/0x250 do_exit+0x564/0x1470 do_group_exit+0x3b/0x100 __do_sys_exit_group+0x13/0x20 __x64_sys_exit_group+0x16/0x20 do_syscall_64+0x34/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Modules linked in: ---[ end trace e99579b570fe0649 ]--- RIP: 0010:release_pages+0x53f/0x840 Link: https://lkml.kernel.org/r/20211221074908.3910286-1-liushixin2@huawei.com Fixes: b94e02822deb ("mm,hwpoison: try to narrow window race for free pages") Signed-off-by: Liu Shixin Reported-by: Hulk Robot Reviewed-by: Oscar Salvador Acked-by: Naoya Horiguchi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/dbgfs: protect targets destructions with kdamond_lock

2021-12-25T20:20:56Z

DAMON debugfs interface iterates current monitoring targets in 'dbgfs_target_ids_read()' while holding the corresponding 'kdamond_lock'. However, it also destructs the monitoring targets in 'dbgfs_before_terminate()' without holding the lock. This can result in a use_after_free bug. This commit avoids the race by protecting the destruction with the corresponding 'kdamond_lock'. Link: https://lkml.kernel.org/r/20211221094447.2241-1-sj@kernel.org Reported-by: Sangwoo Bae Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") Signed-off-by: SeongJae Park Cc: [5.15.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, hwpoison: fix condition in free hugetlb page path

2021-12-25T20:20:55Z

When a memory error hits a tail page of a free hugepage, __page_handle_poison() is expected to be called to isolate the error in 4kB unit, but it's not called due to the outdated if-condition in memory_failure_hugetlb(). This loses the chance to isolate the error in the finer unit, so it's not optimal. Drop the condition. This "(p != head && TestSetPageHWPoison(head)" condition is based on the old semantics of PageHWPoison on hugepage (where PG_hwpoison flag was set on the subpage), so it's not necessray any more. By getting to set PG_hwpoison on head page for hugepages, concurrent error events on different subpages in a single hugepage can be prevented by TestSetPageHWPoison(head) at the beginning of memory_failure_hugetlb(). So dropping the condition should not reopen the race window originally mentioned in commit b985194c8c0a ("hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage") [naoya.horiguchi@linux.dev: fix "HardwareCorrupted" counter] Link: https://lkml.kernel.org/r/20211220084851.GA1460264@u2004 Link: https://lkml.kernel.org/r/20211210110208.879740-1-naoya.horiguchi@linux.dev Signed-off-by: Naoya Horiguchi Reported-by: Fei Luo Reviewed-by: Mike Kravetz Cc: [5.14+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: mempolicy: fix THP allocations escaping mempolicy restrictions

2021-12-25T20:20:55Z

alloc_pages_vma() may try to allocate THP page on the local NUMA node first: page = __alloc_pages_node(hpage_node, gfp | __GFP_THISNODE | __GFP_NORETRY, order); And if the allocation fails it retries allowing remote memory: if (!page && (gfp & __GFP_DIRECT_RECLAIM)) page = __alloc_pages_node(hpage_node, gfp, order); However, this retry allocation completely ignores memory policy nodemask allowing allocation to escape restrictions. The first appearance of this bug seems to be the commit ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings"). The bug disappeared later in the commit 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask") and reappeared again in slightly different form in the commit 76e654cc91bb ("mm, page_alloc: allow hugepage fallback to remote nodes when madvised") Fix this by passing correct nodemask to the __alloc_pages() call. The demonstration/reproducer of the problem: $ mount -oremount,size=4G,huge=always /dev/shm/ $ echo always > /sys/kernel/mm/transparent_hugepage/defrag $ cat mbind_thp.c #include #include #include #include #include #include #include #include #define SIZE 2ULL << 30 int main(int argc, char **argv) { int fd; unsigned long long i; char *addr; pid_t pid; char buf[100]; unsigned long nodemask = 1; fd = open("/dev/shm/test", O_RDWR|O_CREAT); assert(fd > 0); assert(ftruncate(fd, SIZE) == 0); addr = mmap(NULL, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); assert(mbind(addr, SIZE, MPOL_BIND, &nodemask, 2, MPOL_MF_STRICT|MPOL_MF_MOVE)==0); for (i = 0; i < SIZE; i+=4096) { addr[i] = 1; } pid = getpid(); snprintf(buf, sizeof(buf), "grep shm /proc/%d/numa_maps", pid); system(buf); sleep(10000); return 0; } $ gcc mbind_thp.c -o mbind_thp -lnuma $ numactl -H available: 2 nodes (0-1) node 0 cpus: 0 2 node 0 size: 1918 MB node 0 free: 1595 MB node 1 cpus: 1 3 node 1 size: 2014 MB node 1 free: 1731 MB node distances: node 0 1 0: 10 20 1: 20 10 $ rm -f /dev/shm/test; taskset -c 0 ./mbind_thp 7fd970a00000 bind:0 file=/dev/shm/test dirty=524288 active=0 N0=396800 N1=127488 kernelpagesize_kB=4 Link: https://lkml.kernel.org/r/20211208165343.22349-1-arbn@yandex-team.com Fixes: ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings") Signed-off-by: Andrey Ryabinin Acked-by: Michal Hocko Acked-by: Mel Gorman Acked-by: David Rientjes Cc: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kfence: fix memory leak when cat kfence objects

2021-12-25T20:20:55Z

Hulk robot reported a kmemleak problem: unreferenced object 0xffff93d1d8cc02e8 (size 248): comm "cat", pid 23327, jiffies 4624670141 (age 495992.217s) hex dump (first 32 bytes): 00 40 85 19 d4 93 ff ff 00 10 00 00 00 00 00 00 .@.............. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: seq_open+0x2a/0x80 full_proxy_open+0x167/0x1e0 do_dentry_open+0x1e1/0x3a0 path_openat+0x961/0xa20 do_filp_open+0xae/0x120 do_sys_openat2+0x216/0x2f0 do_sys_open+0x57/0x80 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 unreferenced object 0xffff93d419854000 (size 4096): comm "cat", pid 23327, jiffies 4624670141 (age 495992.217s) hex dump (first 32 bytes): 6b 66 65 6e 63 65 2d 23 32 35 30 3a 20 30 78 30 kfence-#250: 0x0 30 30 30 30 30 30 30 37 35 34 62 64 61 31 32 2d 0000000754bda12- backtrace: seq_read_iter+0x313/0x440 seq_read+0x14b/0x1a0 full_proxy_read+0x56/0x80 vfs_read+0xa5/0x1b0 ksys_read+0xa0/0xf0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 I find that we can easily reproduce this problem with the following commands: cat /sys/kernel/debug/kfence/objects echo scan > /sys/kernel/debug/kmemleak cat /sys/kernel/debug/kmemleak The leaked memory is allocated in the stack below: do_syscall_64 do_sys_open do_dentry_open full_proxy_open seq_open ---> alloc seq_file vfs_read full_proxy_read seq_read seq_read_iter traverse ---> alloc seq_buf And it should have been released in the following process: do_syscall_64 syscall_exit_to_user_mode exit_to_user_mode_prepare task_work_run ____fput __fput full_proxy_release ---> free here However, the release function corresponding to file_operations is not implemented in kfence. As a result, a memory leak occurs. Therefore, the solution to this problem is to implement the corresponding release function. Link: https://lkml.kernel.org/r/20211206133628.2822545-1-libaokun1@huawei.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Baokun Li Reported-by: Hulk Robot Acked-by: Marco Elver Reviewed-by: Kefeng Wang Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Yu Kuai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu

2021-12-12T00:14:17Z

Pull percpu fixes from Dennis Zhou: "This contains a fix for SMP && !MMU archs for percpu which has been tested by arm and sh. It seems in the past they have gotten away with it due to mapping of vm functions to km functions, but this fell apart a few releases ago and was just reported recently. The other is just a minor dependency clean up. I think queued up right now by Andrew is a fix in percpu that papers of what seems to be a bug in hotplug for a special situation with memoryless nodes. Michal Hocko is digging into it further" * 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu: percpu_ref: Replace kernel.h with the necessary inclusions percpu: km: ensure it is used with NOMMU (either UP or SMP)

mm: bdi: initialize bdi_min_ratio when bdi is unregistered

2021-12-11T01:10:56Z

Initialize min_ratio if it is set during bdi unregistration. This can prevent problems that may occur a when bdi is removed without resetting min_ratio. For example. 1) insert external sdcard 2) set external sdcard's min_ratio 70 3) remove external sdcard without setting min_ratio 0 4) insert external sdcard 5) set external sdcard's min_ratio 70 << error occur(can't set) Because when an sdcard is removed, the present bdi_min_ratio value will remain. Currently, the only way to reset bdi_min_ratio is to reboot. [akpm@linux-foundation.org: tweak comment and coding style] Link: https://lkml.kernel.org/r/20211021161942.5983-1-mj0123.lee@samsung.com Signed-off-by: Manjong Lee Acked-by: Peter Zijlstra (Intel) Cc: Changheun Lee Cc: Jens Axboe Cc: Christoph Hellwig Cc: Matthew Wilcox Cc: Cc: Cc: Cc: Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds