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Fri, 27 Sep 2024 07:15:03 -0700 (PDT) Date: Fri, 27 Sep 2024 07:15:02 -0700 In-Reply-To: <20240927140018.2164259-1-lizhi.xu@windriver.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <66f6bde6.050a0220.38ace9.0017.GAE@google.com> Subject: Re: [syzbot] [keyrings?] [lsm?] [ext4?] possible deadlock in keyring_clear (2) 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 keyring_clear ====================================================== WARNING: possible circular locking dependency detected 6.11.0-syzkaller-11558-g075dbe9f6e3c-dirty #0 Not tainted ------------------------------------------------------ kswapd0/79 is trying to acquire lock: ffff88804acb05d8 (&type->lock_class){+.+.}-{3:3}, at: keyring_clear+0xb2/0x350 security/keys/keyring.c:1655 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+0xbf1/0x3700 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] assoc_array_clear+0x78/0x1a0 lib/assoc_array.c:1284 keyring_clear+0xc5/0x350 security/keys/keyring.c:1657 fscrypt_put_master_key+0xc8/0x190 fs/crypto/keyring.c:79 fscrypt_initiate_key_removal fs/crypto/keyring.c:137 [inline] fscrypt_destroy_keyring+0x1a7/0x2d0 fs/crypto/keyring.c:259 generic_shutdown_super+0x14a/0x2d0 fs/super.c:648 kill_block_super+0x44/0x90 fs/super.c:1696 ext4_kill_sb+0x68/0xa0 fs/ext4/super.c:7320 deactivate_locked_super+0xc4/0x130 fs/super.c:473 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373 task_work_run+0x24f/0x310 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->lock_class){+.+.}-{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 down_write+0x99/0x220 kernel/locking/rwsem.c:1579 keyring_clear+0xb2/0x350 security/keys/keyring.c:1655 fscrypt_put_master_key+0xc8/0x190 fs/crypto/keyring.c:79 put_crypt_info+0x275/0x320 fs/crypto/keysetup.c:548 fscrypt_put_encryption_info+0x40/0x60 fs/crypto/keysetup.c:753 ext4_clear_inode+0x15b/0x1c0 fs/ext4/super.c:1525 ext4_evict_inode+0xabc/0xf50 fs/ext4/inode.c:323 evict+0x4e8/0x9b0 fs/inode.c:723 __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_memcg mm/shrinker.c:548 [inline] shrink_slab+0x878/0x14d0 mm/shrinker.c:626 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+0x1ca3/0x3700 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(&type->lock_class); lock(fs_reclaim); lock(&type->lock_class); *** DEADLOCK *** 2 locks held by kswapd0/79: #0: ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6844 [inline] #0: ffffffff8ea37100 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x3700 mm/vmscan.c:7226 #1: ffff8880007640e0 (&type->s_umount_key#32){++++}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff8880007640e0 (&type->s_umount_key#32){++++}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196 stack backtrace: CPU: 0 UID: 0 PID: 79 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 down_write+0x99/0x220 kernel/locking/rwsem.c:1579 keyring_clear+0xb2/0x350 security/keys/keyring.c:1655 fscrypt_put_master_key+0xc8/0x190 fs/crypto/keyring.c:79 put_crypt_info+0x275/0x320 fs/crypto/keysetup.c:548 fscrypt_put_encryption_info+0x40/0x60 fs/crypto/keysetup.c:753 ext4_clear_inode+0x15b/0x1c0 fs/ext4/super.c:1525 ext4_evict_inode+0xabc/0xf50 fs/ext4/inode.c:323 evict+0x4e8/0x9b0 fs/inode.c:723 __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_memcg mm/shrinker.c:548 [inline] shrink_slab+0x878/0x14d0 mm/shrinker.c:626 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+0x1ca3/0x3700 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=164306a9980000 kernel config: https://syzkaller.appspot.com/x/.config?x=f6cf7b6189844756 dashboard link: https://syzkaller.appspot.com/bug?extid=1b2d1134e0b675176a15 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=16a4959f980000