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After rename exchanging (either with the rename exchange operation or regular renames in multiple non-atomic steps) two inodes and at least one of them is a directory, we can end up with a log tree that contains only of the inodes and after a power failure that can result in an attempt to delete the other inode when it should not because it was not deleted before the power failure. In some case that delete attempt fails when the target inode is a directory that contains a subvolume inside it, since the log replay code is not prepared to deal with directory entries that point to root items (only inode items). 1) We have directories "dir1" (inode A) and "dir2" (inode B) under the same parent directory; 2) We have a file (inode C) under directory "dir1" (inode A); 3) We have a subvolume inside directory "dir2" (inode B); 4) All these inodes were persisted in a past transaction and we are currently at transaction N; 5) We rename the file (inode C), so at btrfs_log_new_name() we update inode C's last_unlink_trans to N; 6) We get a rename exchange for "dir1" (inode A) and "dir2" (inode B), so after the exchange "dir1" is inode B and "dir2" is inode A. During the rename exchange we call btrfs_log_new_name() for inodes A and B, but because they are directories, we don't update their last_unlink_trans to N; 7) An fsync against the file (inode C) is done, and because its inode has a last_unlink_trans with a value of N we log its parent directory (inode A) (through btrfs_log_all_parents(), called from btrfs_log_inode_parent()). 8) So we end up with inode B not logged, which now has the old name of inode A. At copy_inode_items_to_log(), when logging inode A, we did not check if we had any conflicting inode to log because inode A has a generation lower than the current transaction (created in a past transaction); 9) After a power failure, when replaying the log tree, since we find that inode A has a new name that conflicts with the name of inode B in the fs tree, we attempt to delete inode B... this is wrong since that directory was never deleted before the power failure, and because there is a subvolume inside that directory, attempting to delete it will fail since replay_dir_deletes() and btrfs_unlink_inode() are not prepared to deal with dir items that point to roots instead of inodes. When that happens the mount fails and we get a stack trace like the following: [87.2314] BTRFS info (device dm-0): start tree-log replay [87.2318] BTRFS critical (device dm-0): failed to delete reference to subvol, root 5 inode 256 parent 259 [87.2332] ------------[ cut here ]------------ [87.2338] BTRFS: Transaction aborted (error -2) [87.2346] WARNING: CPU: 1 PID: 638968 at fs/btrfs/inode.c:4345 __btrfs_unlink_inode+0x416/0x440 [btrfs] [87.2368] Modules linked in: btrfs loop dm_thin_pool (...) [87.2470] CPU: 1 UID: 0 PID: 638968 Comm: mount Tainted: G W 6.18.0-rc7-btrfs-next-218+ #2 PREEMPT(full) [87.2489] Tainted: [W]=WARN [87.2494] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [87.2514] RIP: 0010:__btrfs_unlink_inode+0x416/0x440 [btrfs] [87.2538] Code: c0 89 04 24 (...) [87.2568] RSP: 0018:ffffc0e741f4b9b8 EFLAGS: 00010286 [87.2574] RAX: 0000000000000000 RBX: ffff9d3ec8a6cf60 RCX: 0000000000000000 [87.2582] RDX: 0000000000000002 RSI: ffffffff84ab45a1 RDI: 00000000ffffffff [87.2591] RBP: ffff9d3ec8a6ef20 R08: 0000000000000000 R09: ffffc0e741f4b840 [87.2599] R10: ffff9d45dc1fffa8 R11: 0000000000000003 R12: ffff9d3ee26d77e0 [87.2608] R13: ffffc0e741f4ba98 R14: ffff9d4458040800 R15: ffff9d44b6b7ca10 [87.2618] FS: 00007f7b9603a840(0000) GS:ffff9d4658982000(0000) knlGS:0000000000000000 [87.2629] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [87.2637] CR2: 00007ffc9ec33b98 CR3: 000000011273e003 CR4: 0000000000370ef0 [87.2648] Call Trace: [87.2651] <TASK> [87.2654] btrfs_unlink_inode+0x15/0x40 [btrfs] [87.2661] unlink_inode_for_log_replay+0x27/0xf0 [btrfs] [87.2669] check_item_in_log+0x1ea/0x2c0 [btrfs] [87.2676] replay_dir_deletes+0x16b/0x380 [btrfs] [87.2684] fixup_inode_link_count+0x34b/0x370 [btrfs] [87.2696] fixup_inode_link_counts+0x41/0x160 [btrfs] [87.2703] btrfs_recover_log_trees+0x1ff/0x7c0 [btrfs] [87.2711] ? __pfx_replay_one_buffer+0x10/0x10 [btrfs] [87.2719] open_ctree+0x10bb/0x15f0 [btrfs] [87.2726] btrfs_get_tree.cold+0xb/0x16c [btrfs] [87.2734] ? fscontext_read+0x15c/0x180 [87.2740] ? rw_verify_area+0x50/0x180 [87.2746] vfs_get_tree+0x25/0xd0 [87.2750] vfs_cmd_create+0x59/0xe0 [87.2755] __do_sys_fsconfig+0x4f6/0x6b0 [87.2760] do_syscall_64+0x50/0x1220 [87.2764] entry_SYSCALL_64_after_hwframe+0x76/0x7e [87.2770] RIP: 0033:0x7f7b9625f4aa [87.2775] Code: 73 01 c3 48 (...) [87.2803] RSP: 002b:00007ffc9ec35b08 EFLAGS: 00000246 ORIG_RAX: 00000000000001af [87.2817] RAX: ffffffffffffffda RBX: 0000558bfa91ac20 RCX: 00007f7b9625f4aa [87.2829] RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003 [87.2842] RBP: 0000558bfa91b120 R08: 0000000000000000 R09: 0000000000000000 [87.2854] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [87.2864] R13: 00007f7b963f1580 R14: 00007f7b963f326c R15: 00007f7b963d8a23 [87.2877] </TASK> [87.2882] ---[ end trace 0000000000000000 ]--- [87.2891] BTRFS: error (device dm-0 state A) in __btrfs_unlink_inode:4345: errno=-2 No such entry [87.2904] BTRFS: error (device dm-0 state EAO) in do_abort_log_replay:191: errno=-2 No such entry [87.2915] BTRFS critical (device dm-0 state EAO): log tree (for root 5) leaf currently being processed (slot 7 key (258 12 257)): [87.2929] BTRFS info (device dm-0 state EAO): leaf 30736384 gen 10 total ptrs 7 free space 15712 owner 18446744073709551610 [87.2929] BTRFS info (device dm-0 state EAO): refs 3 lock_owner 0 current 638968 [87.2929] item 0 key (257 INODE_ITEM 0) itemoff 16123 itemsize 160 [87.2929] inode generation 9 transid 10 size 0 nbytes 0 [87.2929] block group 0 mode 40755 links 1 uid 0 gid 0 [87.2929] rdev 0 sequence 7 flags 0x0 [87.2929] atime 1765464494.678070921 [87.2929] ctime 1765464494.686606513 [87.2929] mtime 1765464494.686606513 [87.2929] otime 1765464494.678070921 [87.2929] item 1 key (257 INODE_REF 256) itemoff 16109 itemsize 14 [87.2929] index 4 name_len 4 [87.2929] item 2 key (257 DIR_LOG_INDEX 2) itemoff 16101 itemsize 8 [87.2929] dir log end 2 [87.2929] item 3 key (257 DIR_LOG_INDEX 3) itemoff 16093 itemsize 8 [87.2929] dir log end 18446744073709551615 [87.2930] item 4 key (257 DIR_INDEX 3) itemoff 16060 itemsize 33 [87.2930] location key (258 1 0) type 1 [87.2930] transid 10 data_len 0 name_len 3 [87.2930] item 5 key (258 INODE_ITEM 0) itemoff 15900 itemsize 160 [87.2930] inode generation 9 transid 10 size 0 nbytes 0 [87.2930] block group 0 mode 100644 links 1 uid 0 gid 0 [87.2930] rdev 0 sequence 2 flags 0x0 [87.2930] atime 1765464494.678456467 [87.2930] ctime 1765464494.686606513 [87.2930] mtime 1765464494.678456467 [87.2930] otime 1765464494.678456467 [87.2930] item 6 key (258 INODE_REF 257) itemoff 15887 itemsize 13 [87.2930] index 3 name_len 3 [87.2930] BTRFS critical (device dm-0 state EAO): log replay failed in unlink_inode_for_log_replay:1045 for root 5, stage 3, with error -2: failed to unlink inode 256 parent dir 259 name subvol root 5 [87.2963] BTRFS: error (device dm-0 state EAO) in btrfs_recover_log_trees:7743: errno=-2 No such entry [87.2981] BTRFS: error (device dm-0 state EAO) in btrfs_replay_log:2083: errno=-2 No such entry (Failed to recover log tr So fix this by changing copy_inode_items_to_log() to always detect if there are conflicting inodes for the ref/extref of the inode being logged even if the inode was created in a past transaction. A test case for fstests will follow soon. CC: [email protected] # 6.1+ Signed-off-by: Filipe Manana <[email protected]> Signed-off-by: David Sterba <[email protected]>
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…te in qfq_reset `qfq_class->leaf_qdisc->q.qlen > 0` does not imply that the class itself is active. Two qfq_class objects may point to the same leaf_qdisc. This happens when: 1. one QFQ qdisc is attached to the dev as the root qdisc, and 2. another QFQ qdisc is temporarily referenced (e.g., via qdisc_get() / qdisc_put()) and is pending to be destroyed, as in function tc_new_tfilter. When packets are enqueued through the root QFQ qdisc, the shared leaf_qdisc->q.qlen increases. At the same time, the second QFQ qdisc triggers qdisc_put and qdisc_destroy: the qdisc enters qfq_reset() with its own q->q.qlen == 0, but its class's leaf qdisc->q.qlen > 0. Therefore, the qfq_reset would wrongly deactivate an inactive aggregate and trigger a null-deref in qfq_deactivate_agg: [ 0.903172] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 0.903571] #PF: supervisor write access in kernel mode [ 0.903860] #PF: error_code(0x0002) - not-present page [ 0.904177] PGD 10299b067 P4D 10299b067 PUD 10299c067 PMD 0 [ 0.904502] Oops: Oops: 0002 [#1] SMP NOPTI [ 0.904737] CPU: 0 UID: 0 PID: 135 Comm: exploit Not tainted 6.19.0-rc3+ #2 NONE [ 0.905157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 0.905754] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:992 (discriminator 2) include/linux/list.h:1006 (discriminator 2) net/sched/sch_qfq.c:1367 (discriminator 2) net/sched/sch_qfq.c:1393 (discriminator 2)) [ 0.906046] Code: 0f 84 4d 01 00 00 48 89 70 18 8b 4b 10 48 c7 c2 ff ff ff ff 48 8b 78 08 48 d3 e2 48 21 f2 48 2b 13 48 8b 30 48 d3 ea 8b 4b 18 0 Code starting with the faulting instruction =========================================== 0: 0f 84 4d 01 00 00 je 0x153 6: 48 89 70 18 mov %rsi,0x18(%rax) a: 8b 4b 10 mov 0x10(%rbx),%ecx d: 48 c7 c2 ff ff ff ff mov $0xffffffffffffffff,%rdx 14: 48 8b 78 08 mov 0x8(%rax),%rdi 18: 48 d3 e2 shl %cl,%rdx 1b: 48 21 f2 and %rsi,%rdx 1e: 48 2b 13 sub (%rbx),%rdx 21: 48 8b 30 mov (%rax),%rsi 24: 48 d3 ea shr %cl,%rdx 27: 8b 4b 18 mov 0x18(%rbx),%ecx ... [ 0.907095] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246 [ 0.907368] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000 [ 0.907723] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 0.908100] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000 [ 0.908451] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000 [ 0.908804] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880 [ 0.909179] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000 [ 0.909572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.909857] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0 [ 0.910247] PKRU: 55555554 [ 0.910391] Call Trace: [ 0.910527] <TASK> [ 0.910638] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1485) [ 0.910826] qdisc_reset (include/linux/skbuff.h:2195 include/linux/skbuff.h:2501 include/linux/skbuff.h:3424 include/linux/skbuff.h:3430 net/sched/sch_generic.c:1036) [ 0.911040] __qdisc_destroy (net/sched/sch_generic.c:1076) [ 0.911236] tc_new_tfilter (net/sched/cls_api.c:2447) [ 0.911447] rtnetlink_rcv_msg (net/core/rtnetlink.c:6958) [ 0.911663] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6861) [ 0.911894] netlink_rcv_skb (net/netlink/af_netlink.c:2550) [ 0.912100] netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344) [ 0.912296] ? __alloc_skb (net/core/skbuff.c:706) [ 0.912484] netlink_sendmsg (net/netlink/af_netlink.c:1894) [ 0.912682] sock_write_iter (net/socket.c:727 (discriminator 1) net/socket.c:742 (discriminator 1) net/socket.c:1195 (discriminator 1)) [ 0.912880] vfs_write (fs/read_write.c:593 fs/read_write.c:686) [ 0.913077] ksys_write (fs/read_write.c:738) [ 0.913252] do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) [ 0.913438] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:131) [ 0.913687] RIP: 0033:0x424c34 [ 0.913844] Code: 89 02 48 c7 c0 ff ff ff ff eb bd 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 80 3d 2d 44 09 00 00 74 13 b8 01 00 00 00 0f 05 9 Code starting with the faulting instruction =========================================== 0: 89 02 mov %eax,(%rdx) 2: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax 9: eb bd jmp 0xffffffffffffffc8 b: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1) 12: 00 00 00 15: 90 nop 16: f3 0f 1e fa endbr64 1a: 80 3d 2d 44 09 00 00 cmpb $0x0,0x9442d(%rip) # 0x9444e 21: 74 13 je 0x36 23: b8 01 00 00 00 mov $0x1,%eax 28: 0f 05 syscall 2a: 09 .byte 0x9 [ 0.914807] RSP: 002b:00007ffea1938b78 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 [ 0.915197] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000424c34 [ 0.915556] RDX: 000000000000003c RSI: 000000002af378c0 RDI: 0000000000000003 [ 0.915912] RBP: 00007ffea1938bc0 R08: 00000000004b8820 R09: 0000000000000000 [ 0.916297] R10: 0000000000000001 R11: 0000000000000202 R12: 00007ffea1938d28 [ 0.916652] R13: 00007ffea1938d38 R14: 00000000004b3828 R15: 0000000000000001 [ 0.917039] </TASK> [ 0.917158] Modules linked in: [ 0.917316] CR2: 0000000000000000 [ 0.917484] ---[ end trace 0000000000000000 ]--- [ 0.917717] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:992 (discriminator 2) include/linux/list.h:1006 (discriminator 2) net/sched/sch_qfq.c:1367 (discriminator 2) net/sched/sch_qfq.c:1393 (discriminator 2)) [ 0.917978] Code: 0f 84 4d 01 00 00 48 89 70 18 8b 4b 10 48 c7 c2 ff ff ff ff 48 8b 78 08 48 d3 e2 48 21 f2 48 2b 13 48 8b 30 48 d3 ea 8b 4b 18 0 Code starting with the faulting instruction =========================================== 0: 0f 84 4d 01 00 00 je 0x153 6: 48 89 70 18 mov %rsi,0x18(%rax) a: 8b 4b 10 mov 0x10(%rbx),%ecx d: 48 c7 c2 ff ff ff ff mov $0xffffffffffffffff,%rdx 14: 48 8b 78 08 mov 0x8(%rax),%rdi 18: 48 d3 e2 shl %cl,%rdx 1b: 48 21 f2 and %rsi,%rdx 1e: 48 2b 13 sub (%rbx),%rdx 21: 48 8b 30 mov (%rax),%rsi 24: 48 d3 ea shr %cl,%rdx 27: 8b 4b 18 mov 0x18(%rbx),%ecx ... [ 0.918902] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246 [ 0.919198] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000 [ 0.919559] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 0.919908] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000 [ 0.920289] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000 [ 0.920648] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880 [ 0.921014] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000 [ 0.921424] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.921710] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0 [ 0.922097] PKRU: 55555554 [ 0.922240] Kernel panic - not syncing: Fatal exception [ 0.922590] Kernel Offset: disabled Fixes: 0545a30 ("pkt_sched: QFQ - quick fair queue scheduler") Signed-off-by: Xiang Mei <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
Darksonn
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The GPIO controller is configured as non-sleeping but it uses generic
pinctrl helpers which use a mutex for synchronization.
This can cause the following lockdep splat with shared GPIOs enabled on
boards which have multiple devices using the same GPIO:
BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:591
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 12, name:
kworker/u16:0
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
6 locks held by kworker/u16:0/12:
#0: ffff0001f0018d48 ((wq_completion)events_unbound#2){+.+.}-{0:0},
at: process_one_work+0x18c/0x604
#1: ffff8000842dbdf0 (deferred_probe_work){+.+.}-{0:0}, at:
process_one_work+0x1b4/0x604
#2: ffff0001f18498f8 (&dev->mutex){....}-{4:4}, at:
__device_attach+0x38/0x1b0
Rust-for-Linux#3: ffff0001f75f1e90 (&gdev->srcu){.+.?}-{0:0}, at:
gpiod_direction_output_raw_commit+0x0/0x360
Rust-for-Linux#4: ffff0001f46e3db8 (&shared_desc->spinlock){....}-{3:3}, at:
gpio_shared_proxy_direction_output+0xd0/0x144 [gpio_shared_proxy]
Rust-for-Linux#5: ffff0001f180ee90 (&gdev->srcu){.+.?}-{0:0}, at:
gpiod_direction_output_raw_commit+0x0/0x360
irq event stamp: 81450
hardirqs last enabled at (81449): [<ffff8000813acba4>]
_raw_spin_unlock_irqrestore+0x74/0x78
hardirqs last disabled at (81450): [<ffff8000813abfb8>]
_raw_spin_lock_irqsave+0x84/0x88
softirqs last enabled at (79616): [<ffff8000811455fc>]
__alloc_skb+0x17c/0x1e8
softirqs last disabled at (79614): [<ffff8000811455fc>]
__alloc_skb+0x17c/0x1e8
CPU: 2 UID: 0 PID: 12 Comm: kworker/u16:0 Not tainted
6.19.0-rc4-next-20260105+ #11975 PREEMPT
Hardware name: Hardkernel ODROID-M1 (DT)
Workqueue: events_unbound deferred_probe_work_func
Call trace:
show_stack+0x18/0x24 (C)
dump_stack_lvl+0x90/0xd0
dump_stack+0x18/0x24
__might_resched+0x144/0x248
__might_sleep+0x48/0x98
__mutex_lock+0x5c/0x894
mutex_lock_nested+0x24/0x30
pinctrl_get_device_gpio_range+0x44/0x128
pinctrl_gpio_direction+0x3c/0xe0
pinctrl_gpio_direction_output+0x14/0x20
rockchip_gpio_direction_output+0xb8/0x19c
gpiochip_direction_output+0x38/0x94
gpiod_direction_output_raw_commit+0x1d8/0x360
gpiod_direction_output_nonotify+0x7c/0x230
gpiod_direction_output+0x34/0xf8
gpio_shared_proxy_direction_output+0xec/0x144 [gpio_shared_proxy]
gpiochip_direction_output+0x38/0x94
gpiod_direction_output_raw_commit+0x1d8/0x360
gpiod_direction_output_nonotify+0x7c/0x230
gpiod_configure_flags+0xbc/0x480
gpiod_find_and_request+0x1a0/0x574
gpiod_get_index+0x58/0x84
devm_gpiod_get_index+0x20/0xb4
devm_gpiod_get_optional+0x18/0x30
rockchip_pcie_probe+0x98/0x380
platform_probe+0x5c/0xac
really_probe+0xbc/0x298
Fixes: 936ee26 ("gpio/rockchip: add driver for rockchip gpio")
Cc: [email protected]
Reported-by: Marek Szyprowski <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Acked-by: Heiko Stuebner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Bartosz Golaszewski <[email protected]>
Darksonn
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Jan 20, 2026
…ked_inode() In btrfs_read_locked_inode() we are calling btrfs_init_file_extent_tree() while holding a path with a read locked leaf from a subvolume tree, and btrfs_init_file_extent_tree() may do a GFP_KERNEL allocation, which can trigger reclaim. This can create a circular lock dependency which lockdep warns about with the following splat: [6.1433] ====================================================== [6.1574] WARNING: possible circular locking dependency detected [6.1583] 6.18.0+ Rust-for-Linux#4 Tainted: G U [6.1591] ------------------------------------------------------ [6.1599] kswapd0/117 is trying to acquire lock: [6.1606] ffff8d9b6333c5b8 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1625] but task is already holding lock: [6.1633] ffffffffa4ab8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x195/0xc60 [6.1646] which lock already depends on the new lock. [6.1657] the existing dependency chain (in reverse order) is: [6.1667] -> #2 (fs_reclaim){+.+.}-{0:0}: [6.1677] fs_reclaim_acquire+0x9d/0xd0 [6.1685] __kmalloc_cache_noprof+0x59/0x750 [6.1694] btrfs_init_file_extent_tree+0x90/0x100 [6.1702] btrfs_read_locked_inode+0xc3/0x6b0 [6.1710] btrfs_iget+0xbb/0xf0 [6.1716] btrfs_lookup_dentry+0x3c5/0x8e0 [6.1724] btrfs_lookup+0x12/0x30 [6.1731] lookup_open.isra.0+0x1aa/0x6a0 [6.1739] path_openat+0x5f7/0xc60 [6.1746] do_filp_open+0xd6/0x180 [6.1753] do_sys_openat2+0x8b/0xe0 [6.1760] __x64_sys_openat+0x54/0xa0 [6.1768] do_syscall_64+0x97/0x3e0 [6.1776] entry_SYSCALL_64_after_hwframe+0x76/0x7e [6.1784] -> #1 (btrfs-tree-00){++++}-{3:3}: [6.1794] lock_release+0x127/0x2a0 [6.1801] up_read+0x1b/0x30 [6.1808] btrfs_search_slot+0x8e0/0xff0 [6.1817] btrfs_lookup_inode+0x52/0xd0 [6.1825] __btrfs_update_delayed_inode+0x73/0x520 [6.1833] btrfs_commit_inode_delayed_inode+0x11a/0x120 [6.1842] btrfs_log_inode+0x608/0x1aa0 [6.1849] btrfs_log_inode_parent+0x249/0xf80 [6.1857] btrfs_log_dentry_safe+0x3e/0x60 [6.1865] btrfs_sync_file+0x431/0x690 [6.1872] do_fsync+0x39/0x80 [6.1879] __x64_sys_fsync+0x13/0x20 [6.1887] do_syscall_64+0x97/0x3e0 [6.1894] entry_SYSCALL_64_after_hwframe+0x76/0x7e [6.1903] -> #0 (&delayed_node->mutex){+.+.}-{3:3}: [6.1913] __lock_acquire+0x15e9/0x2820 [6.1920] lock_acquire+0xc9/0x2d0 [6.1927] __mutex_lock+0xcc/0x10a0 [6.1934] __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1944] btrfs_evict_inode+0x20b/0x4b0 [6.1952] evict+0x15a/0x2f0 [6.1958] prune_icache_sb+0x91/0xd0 [6.1966] super_cache_scan+0x150/0x1d0 [6.1974] do_shrink_slab+0x155/0x6f0 [6.1981] shrink_slab+0x48e/0x890 [6.1988] shrink_one+0x11a/0x1f0 [6.1995] shrink_node+0xbfd/0x1320 [6.1002] balance_pgdat+0x67f/0xc60 [6.1321] kswapd+0x1dc/0x3e0 [6.1643] kthread+0xff/0x240 [6.1965] ret_from_fork+0x223/0x280 [6.1287] ret_from_fork_asm+0x1a/0x30 [6.1616] other info that might help us debug this: [6.1561] Chain exists of: &delayed_node->mutex --> btrfs-tree-00 --> fs_reclaim [6.1503] Possible unsafe locking scenario: [6.1110] CPU0 CPU1 [6.1411] ---- ---- [6.1707] lock(fs_reclaim); [6.1998] lock(btrfs-tree-00); [6.1291] lock(fs_reclaim); [6.1581] lock(&delayed_node->mutex); [6.1874] *** DEADLOCK *** [6.1716] 2 locks held by kswapd0/117: [6.1999] #0: ffffffffa4ab8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x195/0xc60 [6.1294] #1: ffff8d998344b0e0 (&type->s_umount_key#40){++++}- {3:3}, at: super_cache_scan+0x37/0x1d0 [6.1596] stack backtrace: [6.1183] CPU: 11 UID: 0 PID: 117 Comm: kswapd0 Tainted: G U 6.18.0+ Rust-for-Linux#4 PREEMPT(lazy) [6.1185] Tainted: [U]=USER [6.1186] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 2001 02/01/2023 [6.1187] Call Trace: [6.1187] <TASK> [6.1189] dump_stack_lvl+0x6e/0xa0 [6.1192] print_circular_bug.cold+0x17a/0x1c0 [6.1194] check_noncircular+0x175/0x190 [6.1197] __lock_acquire+0x15e9/0x2820 [6.1200] lock_acquire+0xc9/0x2d0 [6.1201] ? __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1204] __mutex_lock+0xcc/0x10a0 [6.1206] ? __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1208] ? __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1211] ? __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1213] __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1215] btrfs_evict_inode+0x20b/0x4b0 [6.1217] ? lock_acquire+0xc9/0x2d0 [6.1220] evict+0x15a/0x2f0 [6.1222] prune_icache_sb+0x91/0xd0 [6.1224] super_cache_scan+0x150/0x1d0 [6.1226] do_shrink_slab+0x155/0x6f0 [6.1228] shrink_slab+0x48e/0x890 [6.1229] ? shrink_slab+0x2d2/0x890 [6.1231] shrink_one+0x11a/0x1f0 [6.1234] shrink_node+0xbfd/0x1320 [6.1236] ? shrink_node+0xa2d/0x1320 [6.1236] ? shrink_node+0xbd3/0x1320 [6.1239] ? balance_pgdat+0x67f/0xc60 [6.1239] balance_pgdat+0x67f/0xc60 [6.1241] ? finish_task_switch.isra.0+0xc4/0x2a0 [6.1246] kswapd+0x1dc/0x3e0 [6.1247] ? __pfx_autoremove_wake_function+0x10/0x10 [6.1249] ? __pfx_kswapd+0x10/0x10 [6.1250] kthread+0xff/0x240 [6.1251] ? __pfx_kthread+0x10/0x10 [6.1253] ret_from_fork+0x223/0x280 [6.1255] ? __pfx_kthread+0x10/0x10 [6.1257] ret_from_fork_asm+0x1a/0x30 [6.1260] </TASK> This is because: 1) The fsync task is holding an inode's delayed node mutex (for a directory) while calling __btrfs_update_delayed_inode() and that needs to do a search on the subvolume's btree (therefore read lock some extent buffers); 2) The lookup task, at btrfs_lookup(), triggered reclaim with the GFP_KERNEL allocation done by btrfs_init_file_extent_tree() while holding a read lock on a subvolume leaf; 3) The reclaim triggered kswapd which is doing inode eviction for the directory inode the fsync task is using as an argument to btrfs_commit_inode_delayed_inode() - but in that call chain we are trying to read lock the same leaf that the lookup task is holding while calling btrfs_init_file_extent_tree() and doing the GFP_KERNEL allocation. Fix this by calling btrfs_init_file_extent_tree() after we don't need the path anymore and release it in btrfs_read_locked_inode(). Reported-by: Thomas Hellström <[email protected]> Link: https://lore.kernel.org/linux-btrfs/[email protected]/ Fixes: 8679d26 ("btrfs: initialize inode::file_extent_tree after i_mode has been set") Reviewed-by: Qu Wenruo <[email protected]> Signed-off-by: Filipe Manana <[email protected]> Reviewed-by: David Sterba <[email protected]> Signed-off-by: David Sterba <[email protected]>
Darksonn
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Jan 20, 2026
When forward-porting Rust Binder to 6.18, I neglected to take commit fb56fdf ("mm/list_lru: split the lock to per-cgroup scope") into account, and apparently I did not end up running the shrinker callback when I sanity tested the driver before submission. This leads to crashes like the following: ============================================ WARNING: possible recursive locking detected 6.18.0-mainline-maybe-dirty #1 Tainted: G IO -------------------------------------------- kswapd0/68 is trying to acquire lock: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: lock_list_lru_of_memcg+0x128/0x230 but task is already holding lock: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&l->lock); lock(&l->lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kswapd0/68: #0: ffffffff90d2e260 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x597/0x1160 #1: ffff956000fa18b0 (&l->lock){+.+.}-{2:2}, at: rust_helper_spin_lock+0xd/0x20 #2: ffffffff90cf3680 (rcu_read_lock){....}-{1:2}, at: lock_list_lru_of_memcg+0x2d/0x230 To fix this, remove the spin_lock() call from rust_shrink_free_page(). Cc: stable <[email protected]> Fixes: eafedbc ("rust_binder: add Rust Binder driver") Signed-off-by: Alice Ryhl <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
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