possible deadlock in ext4_xattr

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	possible deadlock in ext4_xattr_get	C		inconclusive	1	939d	939d	0/1	upstream: reported C repro on 2022/04/27 03:33
upstream	possible deadlock in ext4_xattr_get ext4	C	inconclusive		3	564d	836d	22/28	fixed on 2023/07/01 16:05

EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue ====================================================== WARNING: possible circular locking dependency detected 4.19.211-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor363/8086 is trying to acquire lock: 00000000bec9b65b (&ei->xattr_sem){++++}, at: ext4_xattr_get+0x141/0x9c0 fs/ext4/xattr.c:648 but task is already holding lock: 00000000bfbe5d25 (&ea_inode->i_rwsem#10/1){+.+.}, at: inode_lock include/linux/fs.h:748 [inline] 00000000bfbe5d25 (&ea_inode->i_rwsem#10/1){+.+.}, at: chown_common+0x2d0/0x550 fs/open.c:648 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&ea_inode->i_rwsem#10/1){+.+.}: inode_lock include/linux/fs.h:748 [inline] ext4_xattr_inode_create fs/ext4/xattr.c:1459 [inline] ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1542 [inline] ext4_xattr_set_entry+0x2a10/0x3750 fs/ext4/xattr.c:1670 ext4_xattr_ibody_set+0x81/0x2a0 fs/ext4/xattr.c:2246 ext4_xattr_set_handle+0x60b/0x1030 fs/ext4/xattr.c:2403 ext4_xattr_set+0x135/0x2a0 fs/ext4/xattr.c:2515 __vfs_setxattr+0x10e/0x170 fs/xattr.c:149 __vfs_setxattr_noperm+0x11a/0x420 fs/xattr.c:180 __vfs_setxattr_locked+0x176/0x250 fs/xattr.c:238 vfs_setxattr+0xe5/0x270 fs/xattr.c:255 setxattr+0x23d/0x330 fs/xattr.c:520 path_setxattr+0x170/0x190 fs/xattr.c:539 __do_sys_setxattr fs/xattr.c:554 [inline] __se_sys_setxattr fs/xattr.c:550 [inline] __x64_sys_setxattr+0xc0/0x160 fs/xattr.c:550 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ei->xattr_sem){++++}: down_read+0x36/0x80 kernel/locking/rwsem.c:24 ext4_xattr_get+0x141/0x9c0 fs/ext4/xattr.c:648 __vfs_getxattr+0xd9/0x140 fs/xattr.c:347 cap_inode_need_killpriv+0x3c/0x60 security/commoncap.c:306 security_inode_need_killpriv+0x40/0x90 security/security.c:797 notify_change+0xa15/0xfc0 fs/attr.c:271 chown_common+0x4a9/0x550 fs/open.c:651 do_fchownat+0x126/0x1e0 fs/open.c:681 __do_sys_fchownat fs/open.c:696 [inline] __se_sys_fchownat fs/open.c:693 [inline] __x64_sys_fchownat+0xba/0x150 fs/open.c:693 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ea_inode->i_rwsem#10/1); lock(&ei->xattr_sem); lock(&ea_inode->i_rwsem#10/1); lock(&ei->xattr_sem); *** DEADLOCK *** 2 locks held by syz-executor363/8086: #0: 000000005b443f8c (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline] #0: 000000005b443f8c (sb_writers#3){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360 #1: 00000000bfbe5d25 (&ea_inode->i_rwsem#10/1){+.+.}, at: inode_lock include/linux/fs.h:748 [inline] #1: 00000000bfbe5d25 (&ea_inode->i_rwsem#10/1){+.+.}, at: chown_common+0x2d0/0x550 fs/open.c:648 stack backtrace: CPU: 0 PID: 8086 Comm: syz-executor363 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2420 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 down_read+0x36/0x80 kernel/locking/rwsem.c:24 ext4_xattr_get+0x141/0x9c0 fs/ext4/xattr.c:648 __vfs_getxattr+0xd9/0x140 fs/xattr.c:347 cap_inode_need_killpriv+0x3c/0x60 security/commoncap.c:306 security_inode_need_killpriv+0x40/0x90 security/security.c:797 notify_change+0xa15/0xfc0 fs/attr.c:271 chown_common+0x4a9/0x550 fs/open.c:651 do_fchownat+0x126/0x1e0 fs/open.c:681 __do_sys_fchownat fs/open.c:696 [inline] __se_sys_fchownat fs/open.c:693 [inline] __x64_sys_fchownat+0xba/0x150 fs/open.c:693 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f2ddf6f4109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffe9617d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000104 RAX: ffffffffffffffda RBX: 2f30656c69662f2e RCX: 00007f2ddf6f4109 RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000005 RBP: 00007f2ddf6b39a0 R08: 0000000000001000 R09: 0000000000000000 R10: 000000000000ee01 R11: 0000000000000246 R12: 00007f2ddf6b3a30 R13: 0000000000000000 R14: 0000000000000000 R15: