Messages in this thread | | | Date | Thu, 29 Dec 2022 01:52:19 -0800 | Subject | Re: [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry | From | syzbot <> |
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Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue: possible deadlock in ext4_find_inline_entry
EXT4-fs: Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none. ====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0 Not tainted ------------------------------------------------------ syz-executor.0/3645 is trying to acquire lock: ffff0000caafc428 (&ei->xattr_sem){++++}-{3:3}, at: ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
but task is already holding lock: ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:757 [inline] ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&ea_inode->i_lockkey){+.+.}-{3:3}: down_write+0x5c/0x88 kernel/locking/rwsem.c:1562 inode_lock include/linux/fs.h:757 [inline] ext4_xattr_inode_create fs/ext4/xattr.c:1455 [inline] ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1538 [inline] ext4_xattr_set_entry+0xdf0/0xe34 fs/ext4/xattr.c:1666 ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2226 ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2383 ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2497 ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38 __vfs_setxattr+0x250/0x260 fs/xattr.c:182 __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216 __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277 vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309 do_setxattr fs/xattr.c:594 [inline] setxattr fs/xattr.c:617 [inline] path_setxattr+0x354/0x414 fs/xattr.c:636 __do_sys_lsetxattr fs/xattr.c:659 [inline] __se_sys_lsetxattr fs/xattr.c:655 [inline] __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
-> #0 (&ei->xattr_sem){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668 down_read+0x5c/0x78 kernel/locking/rwsem.c:1509 ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690 __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596 ext4_find_entry fs/ext4/namei.c:1731 [inline] __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215 ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291 vfs_unlink+0x1dc/0x300 fs/namei.c:4252 do_unlinkat+0x200/0x3dc fs/namei.c:4320 __do_sys_unlinkat fs/namei.c:4363 [inline] __se_sys_unlinkat fs/namei.c:4356 [inline] __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&ea_inode->i_lockkey); lock(&ei->xattr_sem); lock(&ea_inode->i_lockkey); lock(&ei->xattr_sem);
*** DEADLOCK ***
3 locks held by syz-executor.0/3645: #0: ffff0000cba7a460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x20/0x64 fs/namespace.c:393 #1: ffff0000caafc760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:792 [inline] #1: ffff0000caafc760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0xf0/0x3dc fs/namei.c:4303 #2: ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:757 [inline] #2: ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241
stack backtrace: CPU: 1 PID: 3645 Comm: syz-executor.0 Not tainted 6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055 check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177 check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668 down_read+0x5c/0x78 kernel/locking/rwsem.c:1509 ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690 __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596 ext4_find_entry fs/ext4/namei.c:1731 [inline] __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215 ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291 vfs_unlink+0x1dc/0x300 fs/namei.c:4252 do_unlinkat+0x200/0x3dc fs/namei.c:4320 __do_sys_unlinkat fs/namei.c:4363 [inline] __se_sys_unlinkat fs/namei.c:4356 [inline] __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Tested on:
commit: a5541c08 Merge branch 'for-next/core' into for-kernelci git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=12e927f8480000 kernel config: https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397 dashboard link: https://syzkaller.appspot.com/bug?extid=d3bb749184481f92deb5 compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2 userspace arch: arm64 patch: https://syzkaller.appspot.com/x/patch.diff?x=14e927f8480000
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