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Fri, 27 Sep 2024 00:17:05 -0700 (PDT) Date: Fri, 27 Sep 2024 00:17:05 -0700 In-Reply-To: <20240927070001.3435349-1-lizhi.xu@windriver.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <66f65bf1.050a0220.46d20.0010.GAE@google.com> Subject: Re: [syzbot] [squashfs?] possible deadlock in fsnotify_destroy_mark From: syzbot To: linux-kernel@vger.kernel.org, lizhi.xu@windriver.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: possible deadlock in fsnotify_destroy_mark ====================================================== WARNING: possible circular locking dependency detected 6.11.0-syzkaller-11558-g075dbe9f6e3c-dirty #0 Not tainted ------------------------------------------------------ kswapd0/80 is trying to acquire lock: ffff888051323930 (&group->mark_mutex){+.+.}-{3:3}, at: fsnotify_group_lock include/linux/fsnotify_backend.h:270 [inline] ffff888051323930 (&group->mark_mutex){+.+.}-{3:3}, at: fsnotify_destroy_mark+0x38/0x3c0 fs/notify/mark.c:578 but task is already holding lock: ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6844 [inline] ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbb4/0x3590 mm/vmscan.c:7226 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __fs_reclaim_acquire mm/page_alloc.c:3834 [inline] fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3848 might_alloc include/linux/sched/mm.h:327 [inline] slab_pre_alloc_hook mm/slub.c:4037 [inline] slab_alloc_node mm/slub.c:4115 [inline] __kmalloc_cache_noprof+0x3d/0x2c0 mm/slub.c:4291 kmalloc_noprof include/linux/slab.h:878 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] fsnotify_attach_info_to_sb fs/notify/mark.c:626 [inline] fsnotify_add_mark_list fs/notify/mark.c:718 [inline] fsnotify_add_mark_locked+0x3b2/0xdc0 fs/notify/mark.c:803 fsnotify_add_inode_mark_locked include/linux/fsnotify_backend.h:814 [inline] inotify_new_watch fs/notify/inotify/inotify_user.c:620 [inline] inotify_update_watch fs/notify/inotify/inotify_user.c:647 [inline] __do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:786 [inline] __se_sys_inotify_add_watch+0xa83/0x1060 fs/notify/inotify/inotify_user.c:729 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&group->mark_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3158 [inline] check_prevs_add kernel/locking/lockdep.c:3277 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 fsnotify_group_lock include/linux/fsnotify_backend.h:270 [inline] fsnotify_destroy_mark+0x38/0x3c0 fs/notify/mark.c:578 fsnotify_destroy_marks+0x14a/0x660 fs/notify/mark.c:934 fsnotify_inoderemove include/linux/fsnotify.h:264 [inline] dentry_unlink_inode+0x2e0/0x430 fs/dcache.c:408 __dentry_kill+0x20d/0x630 fs/dcache.c:615 shrink_kill+0xa9/0x2c0 fs/dcache.c:1060 shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1087 prune_dcache_sb+0x10f/0x180 fs/dcache.c:1168 super_cache_scan+0x34f/0x4b0 fs/super.c:221 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3799/0x3de0 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1bb4/0x3590 mm/vmscan.c:7226 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&group->mark_mutex); lock(fs_reclaim); lock(&group->mark_mutex); *** DEADLOCK *** 2 locks held by kswapd0/80: #0: ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6844 [inline] #0: ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbb4/0x3590 mm/vmscan.c:7226 #1: ffff8880003380e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff8880003380e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196 stack backtrace: CPU: 0 UID: 0 PID: 80 Comm: kswapd0 Not tainted 6.11.0-syzkaller-11558-g075dbe9f6e3c-dirty #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2203 check_prev_add kernel/locking/lockdep.c:3158 [inline] check_prevs_add kernel/locking/lockdep.c:3277 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3901 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5199 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5822 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 fsnotify_group_lock include/linux/fsnotify_backend.h:270 [inline] fsnotify_destroy_mark+0x38/0x3c0 fs/notify/mark.c:578 fsnotify_destroy_marks+0x14a/0x660 fs/notify/mark.c:934 fsnotify_inoderemove include/linux/fsnotify.h:264 [inline] dentry_unlink_inode+0x2e0/0x430 fs/dcache.c:408 __dentry_kill+0x20d/0x630 fs/dcache.c:615 shrink_kill+0xa9/0x2c0 fs/dcache.c:1060 shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1087 prune_dcache_sb+0x10f/0x180 fs/dcache.c:1168 super_cache_scan+0x34f/0x4b0 fs/super.c:221 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3799/0x3de0 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1bb4/0x3590 mm/vmscan.c:7226 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Tested on: commit: 075dbe9f Merge tag 'soc-ep93xx-dt-6.12' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13eaba80580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5f49dd07427b3bf8 dashboard link: https://syzkaller.appspot.com/bug?extid=c679f13773f295d2da53 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=1736bb3b980000