syzbot

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BUG: KCSAN: data-race in __d_drop / fast_dput

write to 0xffff8881b4dfdc10 of 8 bytes by task 18596 on cpu 0:
 __d_drop+0x14d/0x240 fs/dcache.c:576
 __dentry_kill+0x122/0x460 fs/dcache.c:668
 finish_dput+0x2b/0x200 fs/dcache.c:879
 dput+0x52/0x60 fs/dcache.c:928
 handle_mounts fs/namei.c:1698 [inline]
 step_into_slowpath+0x38c/0x4c0 fs/namei.c:2051
 step_into fs/namei.c:2099 [inline]
 walk_component fs/namei.c:2235 [inline]
 lookup_last fs/namei.c:2730 [inline]
 path_lookupat+0x330/0x500 fs/namei.c:2754
 filename_lookup+0x190/0x390 fs/namei.c:2783
 filename_getxattr+0x54/0x1a0 fs/xattr.c:814
 io_getxattr+0x50/0xe0 io_uring/xattr.c:122
 __io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1793
 io_issue_sqe+0x20b/0xc20 io_uring/io_uring.c:1816
 io_wq_submit_work+0x574/0x770 io_uring/io_uring.c:1928
 io_worker_handle_work+0x41e/0x950 io_uring/io-wq.c:650
 io_wq_worker+0x233/0x910 io_uring/io-wq.c:704
 ret_from_fork+0x148/0x280 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff8881b4dfdc10 of 8 bytes by task 18595 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:366 [inline]
 retain_dentry fs/dcache.c:753 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:849
 dput+0x24/0x60 fs/dcache.c:924
 handle_mounts fs/namei.c:1698 [inline]
 step_into_slowpath+0x38c/0x4c0 fs/namei.c:2051
 step_into fs/namei.c:2099 [inline]
 walk_component fs/namei.c:2235 [inline]
 lookup_last fs/namei.c:2730 [inline]
 path_lookupat+0x330/0x500 fs/namei.c:2754
 filename_lookup+0x190/0x390 fs/namei.c:2783
 filename_getxattr+0x54/0x1a0 fs/xattr.c:814
 io_getxattr+0x50/0xe0 io_uring/xattr.c:122
 __io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1793
 io_issue_sqe+0x20b/0xc20 io_uring/io_uring.c:1816
 io_wq_submit_work+0x574/0x770 io_uring/io_uring.c:1928
 io_worker_handle_work+0x41e/0x950 io_uring/io-wq.c:650
 io_wq_worker+0x233/0x910 io_uring/io-wq.c:704
 ret_from_fork+0x148/0x280 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0xffff888237addc68 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 18595 Comm: iou-wrk-18594 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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