April 2023 - Linux-stable-mirror

FAILED: patch "[PATCH] btrfs: fix deadlock when aborting transaction during" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 2d82a40aa7d6fcae0250ec68b8566cdee7bfd44c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040301-lankiness-entrap-6df8@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 2d82a40aa7d6 ("btrfs: fix deadlock when aborting transaction during relocation with scrub") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2d82a40aa7d6fcae0250ec68b8566cdee7bfd44c Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Wed, 22 Mar 2023 09:46:34 +0000 Subject: [PATCH] btrfs: fix deadlock when aborting transaction during relocation with scrub Before relocating a block group we pause scrub, then do the relocation and then unpause scrub. The relocation process requires starting and committing a transaction, and if we have a failure in the critical section of the transaction commit path (transaction state >= TRANS_STATE_COMMIT_START), we will deadlock if there is a paused scrub. That results in stack traces like the following: [42.479] BTRFS info (device sdc): relocating block group 53876686848 flags metadata|raid6 [42.936] BTRFS warning (device sdc): Skipping commit of aborted transaction. [42.936] ------------[ cut here ]------------ [42.936] BTRFS: Transaction aborted (error -28) [42.936] WARNING: CPU: 11 PID: 346822 at fs/btrfs/transaction.c:1977 btrfs_commit_transaction+0xcc8/0xeb0 [btrfs] [42.936] Modules linked in: dm_flakey dm_mod loop btrfs (...) [42.936] CPU: 11 PID: 346822 Comm: btrfs Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [42.936] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [42.936] RIP: 0010:btrfs_commit_transaction+0xcc8/0xeb0 [btrfs] [42.936] Code: ff ff 45 8b (...) [42.936] RSP: 0018:ffffb58649633b48 EFLAGS: 00010282 [42.936] RAX: 0000000000000000 RBX: ffff8be6ef4d5bd8 RCX: 0000000000000000 [42.936] RDX: 0000000000000002 RSI: ffffffffb35e7782 RDI: 00000000ffffffff [42.936] RBP: ffff8be6ef4d5c98 R08: 0000000000000000 R09: ffffb586496339e8 [42.936] R10: 0000000000000001 R11: 0000000000000001 R12: ffff8be6d38c7c00 [42.936] R13: 00000000ffffffe4 R14: ffff8be6c268c000 R15: ffff8be6ef4d5cf0 [42.936] FS: 00007f381a82b340(0000) GS:ffff8beddfcc0000(0000) knlGS:0000000000000000 [42.936] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [42.936] CR2: 00007f1e35fb7638 CR3: 0000000117680006 CR4: 0000000000370ee0 [42.936] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [42.936] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [42.936] Call Trace: [42.936] <TASK> [42.936] ? start_transaction+0xcb/0x610 [btrfs] [42.936] prepare_to_relocate+0x111/0x1a0 [btrfs] [42.936] relocate_block_group+0x57/0x5d0 [btrfs] [42.936] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs] [42.936] btrfs_relocate_block_group+0x248/0x3c0 [btrfs] [42.936] ? __pfx_autoremove_wake_function+0x10/0x10 [42.936] btrfs_relocate_chunk+0x3b/0x150 [btrfs] [42.936] btrfs_balance+0x8ff/0x11d0 [btrfs] [42.936] ? __kmem_cache_alloc_node+0x14a/0x410 [42.936] btrfs_ioctl+0x2334/0x32c0 [btrfs] [42.937] ? mod_objcg_state+0xd2/0x360 [42.937] ? refill_obj_stock+0xb0/0x160 [42.937] ? seq_release+0x25/0x30 [42.937] ? __rseq_handle_notify_resume+0x3b5/0x4b0 [42.937] ? percpu_counter_add_batch+0x2e/0xa0 [42.937] ? __x64_sys_ioctl+0x88/0xc0 [42.937] __x64_sys_ioctl+0x88/0xc0 [42.937] do_syscall_64+0x38/0x90 [42.937] entry_SYSCALL_64_after_hwframe+0x72/0xdc [42.937] RIP: 0033:0x7f381a6ffe9b [42.937] Code: 00 48 89 44 24 (...) [42.937] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [42.937] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b [42.937] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003 [42.937] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000 [42.937] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423 [42.937] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148 [42.937] </TASK> [42.937] ---[ end trace 0000000000000000 ]--- [42.937] BTRFS: error (device sdc: state A) in cleanup_transaction:1977: errno=-28 No space left [59.196] INFO: task btrfs:346772 blocked for more than 120 seconds. [59.196] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.196] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.196] task:btrfs state:D stack:0 pid:346772 ppid:1 flags:0x00004002 [59.196] Call Trace: [59.196] <TASK> [59.196] __schedule+0x392/0xa70 [59.196] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.196] schedule+0x5d/0xd0 [59.196] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.197] ? __pfx_autoremove_wake_function+0x10/0x10 [59.197] scrub_pause_off+0x21/0x50 [btrfs] [59.197] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.197] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.198] ? __pfx_autoremove_wake_function+0x10/0x10 [59.198] scrub_stripe+0x20d/0x740 [btrfs] [59.198] scrub_chunk+0xc4/0x130 [btrfs] [59.198] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.198] ? __pfx_autoremove_wake_function+0x10/0x10 [59.198] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.199] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.199] ? _copy_from_user+0x7b/0x80 [59.199] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.199] ? refill_stock+0x33/0x50 [59.199] ? should_failslab+0xa/0x20 [59.199] ? kmem_cache_alloc_node+0x151/0x460 [59.199] ? alloc_io_context+0x1b/0x80 [59.199] ? preempt_count_add+0x70/0xa0 [59.199] ? __x64_sys_ioctl+0x88/0xc0 [59.199] __x64_sys_ioctl+0x88/0xc0 [59.199] do_syscall_64+0x38/0x90 [59.199] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.199] RIP: 0033:0x7f82ffaffe9b [59.199] RSP: 002b:00007f82ff9fcc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.199] RAX: ffffffffffffffda RBX: 000055b191e36310 RCX: 00007f82ffaffe9b [59.199] RDX: 000055b191e36310 RSI: 00000000c400941b RDI: 0000000000000003 [59.199] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.199] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff9fd640 [59.199] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.199] </TASK> [59.199] INFO: task btrfs:346773 blocked for more than 120 seconds. [59.200] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.200] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.201] task:btrfs state:D stack:0 pid:346773 ppid:1 flags:0x00004002 [59.201] Call Trace: [59.201] <TASK> [59.201] __schedule+0x392/0xa70 [59.201] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.201] schedule+0x5d/0xd0 [59.201] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.201] ? __pfx_autoremove_wake_function+0x10/0x10 [59.201] scrub_pause_off+0x21/0x50 [btrfs] [59.202] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.202] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.202] ? __pfx_autoremove_wake_function+0x10/0x10 [59.202] scrub_stripe+0x20d/0x740 [btrfs] [59.202] scrub_chunk+0xc4/0x130 [btrfs] [59.203] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.203] ? __pfx_autoremove_wake_function+0x10/0x10 [59.203] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.203] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.203] ? _copy_from_user+0x7b/0x80 [59.203] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.204] ? should_failslab+0xa/0x20 [59.204] ? kmem_cache_alloc_node+0x151/0x460 [59.204] ? alloc_io_context+0x1b/0x80 [59.204] ? preempt_count_add+0x70/0xa0 [59.204] ? __x64_sys_ioctl+0x88/0xc0 [59.204] __x64_sys_ioctl+0x88/0xc0 [59.204] do_syscall_64+0x38/0x90 [59.204] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.204] RIP: 0033:0x7f82ffaffe9b [59.204] RSP: 002b:00007f82ff1fbc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.204] RAX: ffffffffffffffda RBX: 000055b191e36790 RCX: 00007f82ffaffe9b [59.204] RDX: 000055b191e36790 RSI: 00000000c400941b RDI: 0000000000000003 [59.204] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.204] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff1fc640 [59.204] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.204] </TASK> [59.204] INFO: task btrfs:346774 blocked for more than 120 seconds. [59.205] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.205] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.206] task:btrfs state:D stack:0 pid:346774 ppid:1 flags:0x00004002 [59.206] Call Trace: [59.206] <TASK> [59.206] __schedule+0x392/0xa70 [59.206] schedule+0x5d/0xd0 [59.206] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.206] ? __pfx_autoremove_wake_function+0x10/0x10 [59.206] scrub_pause_off+0x21/0x50 [btrfs] [59.207] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.207] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.207] ? __pfx_autoremove_wake_function+0x10/0x10 [59.207] scrub_stripe+0x20d/0x740 [btrfs] [59.208] scrub_chunk+0xc4/0x130 [btrfs] [59.208] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.208] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120 [59.208] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.208] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.209] ? _copy_from_user+0x7b/0x80 [59.209] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.209] ? should_failslab+0xa/0x20 [59.209] ? kmem_cache_alloc_node+0x151/0x460 [59.209] ? alloc_io_context+0x1b/0x80 [59.209] ? preempt_count_add+0x70/0xa0 [59.209] ? __x64_sys_ioctl+0x88/0xc0 [59.209] __x64_sys_ioctl+0x88/0xc0 [59.209] do_syscall_64+0x38/0x90 [59.209] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.209] RIP: 0033:0x7f82ffaffe9b [59.209] RSP: 002b:00007f82fe9fac50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.209] RAX: ffffffffffffffda RBX: 000055b191e36c10 RCX: 00007f82ffaffe9b [59.209] RDX: 000055b191e36c10 RSI: 00000000c400941b RDI: 0000000000000003 [59.209] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.209] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe9fb640 [59.209] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.209] </TASK> [59.209] INFO: task btrfs:346775 blocked for more than 120 seconds. [59.210] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.210] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.211] task:btrfs state:D stack:0 pid:346775 ppid:1 flags:0x00004002 [59.211] Call Trace: [59.211] <TASK> [59.211] __schedule+0x392/0xa70 [59.211] schedule+0x5d/0xd0 [59.211] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.211] ? __pfx_autoremove_wake_function+0x10/0x10 [59.211] scrub_pause_off+0x21/0x50 [btrfs] [59.212] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.212] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.212] ? __pfx_autoremove_wake_function+0x10/0x10 [59.212] scrub_stripe+0x20d/0x740 [btrfs] [59.213] scrub_chunk+0xc4/0x130 [btrfs] [59.213] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.213] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120 [59.213] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.213] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.214] ? _copy_from_user+0x7b/0x80 [59.214] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.214] ? should_failslab+0xa/0x20 [59.214] ? kmem_cache_alloc_node+0x151/0x460 [59.214] ? alloc_io_context+0x1b/0x80 [59.214] ? preempt_count_add+0x70/0xa0 [59.214] ? __x64_sys_ioctl+0x88/0xc0 [59.214] __x64_sys_ioctl+0x88/0xc0 [59.214] do_syscall_64+0x38/0x90 [59.214] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.214] RIP: 0033:0x7f82ffaffe9b [59.214] RSP: 002b:00007f82fe1f9c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.214] RAX: ffffffffffffffda RBX: 000055b191e37090 RCX: 00007f82ffaffe9b [59.214] RDX: 000055b191e37090 RSI: 00000000c400941b RDI: 0000000000000003 [59.214] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.214] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe1fa640 [59.214] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.214] </TASK> [59.214] INFO: task btrfs:346776 blocked for more than 120 seconds. [59.215] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.216] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.217] task:btrfs state:D stack:0 pid:346776 ppid:1 flags:0x00004002 [59.217] Call Trace: [59.217] <TASK> [59.217] __schedule+0x392/0xa70 [59.217] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.217] schedule+0x5d/0xd0 [59.217] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.217] ? __pfx_autoremove_wake_function+0x10/0x10 [59.217] scrub_pause_off+0x21/0x50 [btrfs] [59.217] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.217] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.218] ? __pfx_autoremove_wake_function+0x10/0x10 [59.218] scrub_stripe+0x20d/0x740 [btrfs] [59.218] scrub_chunk+0xc4/0x130 [btrfs] [59.218] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.219] ? __pfx_autoremove_wake_function+0x10/0x10 [59.219] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.219] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.219] ? _copy_from_user+0x7b/0x80 [59.219] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.219] ? should_failslab+0xa/0x20 [59.219] ? kmem_cache_alloc_node+0x151/0x460 [59.219] ? alloc_io_context+0x1b/0x80 [59.219] ? preempt_count_add+0x70/0xa0 [59.219] ? __x64_sys_ioctl+0x88/0xc0 [59.219] __x64_sys_ioctl+0x88/0xc0 [59.219] do_syscall_64+0x38/0x90 [59.219] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.219] RIP: 0033:0x7f82ffaffe9b [59.219] RSP: 002b:00007f82fd9f8c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.219] RAX: ffffffffffffffda RBX: 000055b191e37510 RCX: 00007f82ffaffe9b [59.219] RDX: 000055b191e37510 RSI: 00000000c400941b RDI: 0000000000000003 [59.219] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.219] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fd9f9640 [59.219] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.219] </TASK> [59.219] INFO: task btrfs:346822 blocked for more than 120 seconds. [59.220] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.221] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.222] task:btrfs state:D stack:0 pid:346822 ppid:1 flags:0x00004002 [59.222] Call Trace: [59.222] <TASK> [59.222] __schedule+0x392/0xa70 [59.222] schedule+0x5d/0xd0 [59.222] btrfs_scrub_cancel+0x91/0x100 [btrfs] [59.222] ? __pfx_autoremove_wake_function+0x10/0x10 [59.222] btrfs_commit_transaction+0x572/0xeb0 [btrfs] [59.223] ? start_transaction+0xcb/0x610 [btrfs] [59.223] prepare_to_relocate+0x111/0x1a0 [btrfs] [59.223] relocate_block_group+0x57/0x5d0 [btrfs] [59.223] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs] [59.223] btrfs_relocate_block_group+0x248/0x3c0 [btrfs] [59.224] ? __pfx_autoremove_wake_function+0x10/0x10 [59.224] btrfs_relocate_chunk+0x3b/0x150 [btrfs] [59.224] btrfs_balance+0x8ff/0x11d0 [btrfs] [59.224] ? __kmem_cache_alloc_node+0x14a/0x410 [59.224] btrfs_ioctl+0x2334/0x32c0 [btrfs] [59.225] ? mod_objcg_state+0xd2/0x360 [59.225] ? refill_obj_stock+0xb0/0x160 [59.225] ? seq_release+0x25/0x30 [59.225] ? __rseq_handle_notify_resume+0x3b5/0x4b0 [59.225] ? percpu_counter_add_batch+0x2e/0xa0 [59.225] ? __x64_sys_ioctl+0x88/0xc0 [59.225] __x64_sys_ioctl+0x88/0xc0 [59.225] do_syscall_64+0x38/0x90 [59.225] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.225] RIP: 0033:0x7f381a6ffe9b [59.225] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.225] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b [59.225] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003 [59.225] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000 [59.225] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423 [59.225] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148 [59.225] </TASK> What happens is the following: 1) A scrub is running, so fs_info->scrubs_running is 1; 2) Task A starts block group relocation, and at btrfs_relocate_chunk() it pauses scrub by calling btrfs_scrub_pause(). That increments fs_info->scrub_pause_req from 0 to 1 and waits for the scrub task to pause (for fs_info->scrubs_paused to be == to fs_info->scrubs_running); 3) The scrub task pauses at scrub_pause_off(), waiting for fs_info->scrub_pause_req to decrease to 0; 4) Task A then enters btrfs_relocate_block_group(), and down that call chain we start a transaction and then attempt to commit it; 5) When task A calls btrfs_commit_transaction(), it either will do the commit itself or wait for some other task that already started the commit of the transaction - it doesn't matter which case; 6) The transaction commit enters state TRANS_STATE_COMMIT_START; 7) An error happens during the transaction commit, like -ENOSPC when running delayed refs or delayed items for example; 8) This results in calling transaction.c:cleanup_transaction(), where we call btrfs_scrub_cancel(), incrementing fs_info->scrub_cancel_req from 0 to 1, and blocking this task waiting for fs_info->scrubs_running to decrease to 0; 9) From this point on, both the transaction commit and the scrub task hang forever: 1) The transaction commit is waiting for fs_info->scrubs_running to be decreased to 0; 2) The scrub task is at scrub_pause_off() waiting for fs_info->scrub_pause_req to decrease to 0 - so it can not proceed to stop the scrub and decrement fs_info->scrubs_running from 0 to 1. Therefore resulting in a deadlock. Fix this by having cleanup_transaction(), called if a transaction commit fails, not call btrfs_scrub_cancel() if relocation is in progress, and having btrfs_relocate_block_group() call btrfs_scrub_cancel() instead if the relocation failed and a transaction abort happened. This was triggered with btrfs/061 from fstests. Fixes: 55e3a601c81c ("btrfs: Fix data checksum error cause by replace with io-load.") CC: stable(a)vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 18329ebcb1cb..b8d5b1fa9a03 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -2035,7 +2035,20 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err) if (current->journal_info == trans) current->journal_info = NULL; - btrfs_scrub_cancel(fs_info); + + /* + * If relocation is running, we can't cancel scrub because that will + * result in a deadlock. Before relocating a block group, relocation + * pauses scrub, then starts and commits a transaction before unpausing + * scrub. If the transaction commit is being done by the relocation + * task or triggered by another task and the relocation task is waiting + * for the commit, and we end up here due to an error in the commit + * path, then calling btrfs_scrub_cancel() will deadlock, as we are + * asking for scrub to stop while having it asked to be paused higher + * above in relocation code. + */ + if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) + btrfs_scrub_cancel(fs_info); kmem_cache_free(btrfs_trans_handle_cachep, trans); } diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index ac0e8fb92fc8..c6d592870400 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3275,8 +3275,15 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) btrfs_scrub_pause(fs_info); ret = btrfs_relocate_block_group(fs_info, chunk_offset); btrfs_scrub_continue(fs_info); - if (ret) + if (ret) { + /* + * If we had a transaction abort, stop all running scrubs. + * See transaction.c:cleanup_transaction() why we do it here. + */ + if (BTRFS_FS_ERROR(fs_info)) + btrfs_scrub_cancel(fs_info); return ret; + } block_group = btrfs_lookup_block_group(fs_info, chunk_offset); if (!block_group)

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: fix deadlock when aborting transaction during" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 2d82a40aa7d6fcae0250ec68b8566cdee7bfd44c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040353-grumpily-nastily-93b2@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 2d82a40aa7d6 ("btrfs: fix deadlock when aborting transaction during relocation with scrub") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2d82a40aa7d6fcae0250ec68b8566cdee7bfd44c Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Wed, 22 Mar 2023 09:46:34 +0000 Subject: [PATCH] btrfs: fix deadlock when aborting transaction during relocation with scrub Before relocating a block group we pause scrub, then do the relocation and then unpause scrub. The relocation process requires starting and committing a transaction, and if we have a failure in the critical section of the transaction commit path (transaction state >= TRANS_STATE_COMMIT_START), we will deadlock if there is a paused scrub. That results in stack traces like the following: [42.479] BTRFS info (device sdc): relocating block group 53876686848 flags metadata|raid6 [42.936] BTRFS warning (device sdc): Skipping commit of aborted transaction. [42.936] ------------[ cut here ]------------ [42.936] BTRFS: Transaction aborted (error -28) [42.936] WARNING: CPU: 11 PID: 346822 at fs/btrfs/transaction.c:1977 btrfs_commit_transaction+0xcc8/0xeb0 [btrfs] [42.936] Modules linked in: dm_flakey dm_mod loop btrfs (...) [42.936] CPU: 11 PID: 346822 Comm: btrfs Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [42.936] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [42.936] RIP: 0010:btrfs_commit_transaction+0xcc8/0xeb0 [btrfs] [42.936] Code: ff ff 45 8b (...) [42.936] RSP: 0018:ffffb58649633b48 EFLAGS: 00010282 [42.936] RAX: 0000000000000000 RBX: ffff8be6ef4d5bd8 RCX: 0000000000000000 [42.936] RDX: 0000000000000002 RSI: ffffffffb35e7782 RDI: 00000000ffffffff [42.936] RBP: ffff8be6ef4d5c98 R08: 0000000000000000 R09: ffffb586496339e8 [42.936] R10: 0000000000000001 R11: 0000000000000001 R12: ffff8be6d38c7c00 [42.936] R13: 00000000ffffffe4 R14: ffff8be6c268c000 R15: ffff8be6ef4d5cf0 [42.936] FS: 00007f381a82b340(0000) GS:ffff8beddfcc0000(0000) knlGS:0000000000000000 [42.936] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [42.936] CR2: 00007f1e35fb7638 CR3: 0000000117680006 CR4: 0000000000370ee0 [42.936] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [42.936] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [42.936] Call Trace: [42.936] <TASK> [42.936] ? start_transaction+0xcb/0x610 [btrfs] [42.936] prepare_to_relocate+0x111/0x1a0 [btrfs] [42.936] relocate_block_group+0x57/0x5d0 [btrfs] [42.936] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs] [42.936] btrfs_relocate_block_group+0x248/0x3c0 [btrfs] [42.936] ? __pfx_autoremove_wake_function+0x10/0x10 [42.936] btrfs_relocate_chunk+0x3b/0x150 [btrfs] [42.936] btrfs_balance+0x8ff/0x11d0 [btrfs] [42.936] ? __kmem_cache_alloc_node+0x14a/0x410 [42.936] btrfs_ioctl+0x2334/0x32c0 [btrfs] [42.937] ? mod_objcg_state+0xd2/0x360 [42.937] ? refill_obj_stock+0xb0/0x160 [42.937] ? seq_release+0x25/0x30 [42.937] ? __rseq_handle_notify_resume+0x3b5/0x4b0 [42.937] ? percpu_counter_add_batch+0x2e/0xa0 [42.937] ? __x64_sys_ioctl+0x88/0xc0 [42.937] __x64_sys_ioctl+0x88/0xc0 [42.937] do_syscall_64+0x38/0x90 [42.937] entry_SYSCALL_64_after_hwframe+0x72/0xdc [42.937] RIP: 0033:0x7f381a6ffe9b [42.937] Code: 00 48 89 44 24 (...) [42.937] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [42.937] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b [42.937] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003 [42.937] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000 [42.937] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423 [42.937] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148 [42.937] </TASK> [42.937] ---[ end trace 0000000000000000 ]--- [42.937] BTRFS: error (device sdc: state A) in cleanup_transaction:1977: errno=-28 No space left [59.196] INFO: task btrfs:346772 blocked for more than 120 seconds. [59.196] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.196] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.196] task:btrfs state:D stack:0 pid:346772 ppid:1 flags:0x00004002 [59.196] Call Trace: [59.196] <TASK> [59.196] __schedule+0x392/0xa70 [59.196] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.196] schedule+0x5d/0xd0 [59.196] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.197] ? __pfx_autoremove_wake_function+0x10/0x10 [59.197] scrub_pause_off+0x21/0x50 [btrfs] [59.197] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.197] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.198] ? __pfx_autoremove_wake_function+0x10/0x10 [59.198] scrub_stripe+0x20d/0x740 [btrfs] [59.198] scrub_chunk+0xc4/0x130 [btrfs] [59.198] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.198] ? __pfx_autoremove_wake_function+0x10/0x10 [59.198] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.199] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.199] ? _copy_from_user+0x7b/0x80 [59.199] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.199] ? refill_stock+0x33/0x50 [59.199] ? should_failslab+0xa/0x20 [59.199] ? kmem_cache_alloc_node+0x151/0x460 [59.199] ? alloc_io_context+0x1b/0x80 [59.199] ? preempt_count_add+0x70/0xa0 [59.199] ? __x64_sys_ioctl+0x88/0xc0 [59.199] __x64_sys_ioctl+0x88/0xc0 [59.199] do_syscall_64+0x38/0x90 [59.199] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.199] RIP: 0033:0x7f82ffaffe9b [59.199] RSP: 002b:00007f82ff9fcc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.199] RAX: ffffffffffffffda RBX: 000055b191e36310 RCX: 00007f82ffaffe9b [59.199] RDX: 000055b191e36310 RSI: 00000000c400941b RDI: 0000000000000003 [59.199] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.199] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff9fd640 [59.199] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.199] </TASK> [59.199] INFO: task btrfs:346773 blocked for more than 120 seconds. [59.200] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.200] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.201] task:btrfs state:D stack:0 pid:346773 ppid:1 flags:0x00004002 [59.201] Call Trace: [59.201] <TASK> [59.201] __schedule+0x392/0xa70 [59.201] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.201] schedule+0x5d/0xd0 [59.201] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.201] ? __pfx_autoremove_wake_function+0x10/0x10 [59.201] scrub_pause_off+0x21/0x50 [btrfs] [59.202] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.202] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.202] ? __pfx_autoremove_wake_function+0x10/0x10 [59.202] scrub_stripe+0x20d/0x740 [btrfs] [59.202] scrub_chunk+0xc4/0x130 [btrfs] [59.203] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.203] ? __pfx_autoremove_wake_function+0x10/0x10 [59.203] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.203] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.203] ? _copy_from_user+0x7b/0x80 [59.203] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.204] ? should_failslab+0xa/0x20 [59.204] ? kmem_cache_alloc_node+0x151/0x460 [59.204] ? alloc_io_context+0x1b/0x80 [59.204] ? preempt_count_add+0x70/0xa0 [59.204] ? __x64_sys_ioctl+0x88/0xc0 [59.204] __x64_sys_ioctl+0x88/0xc0 [59.204] do_syscall_64+0x38/0x90 [59.204] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.204] RIP: 0033:0x7f82ffaffe9b [59.204] RSP: 002b:00007f82ff1fbc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.204] RAX: ffffffffffffffda RBX: 000055b191e36790 RCX: 00007f82ffaffe9b [59.204] RDX: 000055b191e36790 RSI: 00000000c400941b RDI: 0000000000000003 [59.204] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.204] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff1fc640 [59.204] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.204] </TASK> [59.204] INFO: task btrfs:346774 blocked for more than 120 seconds. [59.205] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.205] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.206] task:btrfs state:D stack:0 pid:346774 ppid:1 flags:0x00004002 [59.206] Call Trace: [59.206] <TASK> [59.206] __schedule+0x392/0xa70 [59.206] schedule+0x5d/0xd0 [59.206] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.206] ? __pfx_autoremove_wake_function+0x10/0x10 [59.206] scrub_pause_off+0x21/0x50 [btrfs] [59.207] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.207] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.207] ? __pfx_autoremove_wake_function+0x10/0x10 [59.207] scrub_stripe+0x20d/0x740 [btrfs] [59.208] scrub_chunk+0xc4/0x130 [btrfs] [59.208] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.208] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120 [59.208] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.208] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.209] ? _copy_from_user+0x7b/0x80 [59.209] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.209] ? should_failslab+0xa/0x20 [59.209] ? kmem_cache_alloc_node+0x151/0x460 [59.209] ? alloc_io_context+0x1b/0x80 [59.209] ? preempt_count_add+0x70/0xa0 [59.209] ? __x64_sys_ioctl+0x88/0xc0 [59.209] __x64_sys_ioctl+0x88/0xc0 [59.209] do_syscall_64+0x38/0x90 [59.209] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.209] RIP: 0033:0x7f82ffaffe9b [59.209] RSP: 002b:00007f82fe9fac50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.209] RAX: ffffffffffffffda RBX: 000055b191e36c10 RCX: 00007f82ffaffe9b [59.209] RDX: 000055b191e36c10 RSI: 00000000c400941b RDI: 0000000000000003 [59.209] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.209] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe9fb640 [59.209] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.209] </TASK> [59.209] INFO: task btrfs:346775 blocked for more than 120 seconds. [59.210] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.210] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.211] task:btrfs state:D stack:0 pid:346775 ppid:1 flags:0x00004002 [59.211] Call Trace: [59.211] <TASK> [59.211] __schedule+0x392/0xa70 [59.211] schedule+0x5d/0xd0 [59.211] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.211] ? __pfx_autoremove_wake_function+0x10/0x10 [59.211] scrub_pause_off+0x21/0x50 [btrfs] [59.212] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.212] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.212] ? __pfx_autoremove_wake_function+0x10/0x10 [59.212] scrub_stripe+0x20d/0x740 [btrfs] [59.213] scrub_chunk+0xc4/0x130 [btrfs] [59.213] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.213] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120 [59.213] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.213] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.214] ? _copy_from_user+0x7b/0x80 [59.214] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.214] ? should_failslab+0xa/0x20 [59.214] ? kmem_cache_alloc_node+0x151/0x460 [59.214] ? alloc_io_context+0x1b/0x80 [59.214] ? preempt_count_add+0x70/0xa0 [59.214] ? __x64_sys_ioctl+0x88/0xc0 [59.214] __x64_sys_ioctl+0x88/0xc0 [59.214] do_syscall_64+0x38/0x90 [59.214] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.214] RIP: 0033:0x7f82ffaffe9b [59.214] RSP: 002b:00007f82fe1f9c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.214] RAX: ffffffffffffffda RBX: 000055b191e37090 RCX: 00007f82ffaffe9b [59.214] RDX: 000055b191e37090 RSI: 00000000c400941b RDI: 0000000000000003 [59.214] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.214] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe1fa640 [59.214] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.214] </TASK> [59.214] INFO: task btrfs:346776 blocked for more than 120 seconds. [59.215] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.216] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.217] task:btrfs state:D stack:0 pid:346776 ppid:1 flags:0x00004002 [59.217] Call Trace: [59.217] <TASK> [59.217] __schedule+0x392/0xa70 [59.217] ? __pv_queued_spin_lock_slowpath+0x165/0x370 [59.217] schedule+0x5d/0xd0 [59.217] __scrub_blocked_if_needed+0x74/0xc0 [btrfs] [59.217] ? __pfx_autoremove_wake_function+0x10/0x10 [59.217] scrub_pause_off+0x21/0x50 [btrfs] [59.217] scrub_simple_mirror+0x1c7/0x950 [btrfs] [59.217] ? scrub_parity_put+0x1a5/0x1d0 [btrfs] [59.218] ? __pfx_autoremove_wake_function+0x10/0x10 [59.218] scrub_stripe+0x20d/0x740 [btrfs] [59.218] scrub_chunk+0xc4/0x130 [btrfs] [59.218] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs] [59.219] ? __pfx_autoremove_wake_function+0x10/0x10 [59.219] btrfs_scrub_dev+0x236/0x6a0 [btrfs] [59.219] ? btrfs_ioctl+0xd97/0x32c0 [btrfs] [59.219] ? _copy_from_user+0x7b/0x80 [59.219] btrfs_ioctl+0xde1/0x32c0 [btrfs] [59.219] ? should_failslab+0xa/0x20 [59.219] ? kmem_cache_alloc_node+0x151/0x460 [59.219] ? alloc_io_context+0x1b/0x80 [59.219] ? preempt_count_add+0x70/0xa0 [59.219] ? __x64_sys_ioctl+0x88/0xc0 [59.219] __x64_sys_ioctl+0x88/0xc0 [59.219] do_syscall_64+0x38/0x90 [59.219] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.219] RIP: 0033:0x7f82ffaffe9b [59.219] RSP: 002b:00007f82fd9f8c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.219] RAX: ffffffffffffffda RBX: 000055b191e37510 RCX: 00007f82ffaffe9b [59.219] RDX: 000055b191e37510 RSI: 00000000c400941b RDI: 0000000000000003 [59.219] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000 [59.219] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fd9f9640 [59.219] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000 [59.219] </TASK> [59.219] INFO: task btrfs:346822 blocked for more than 120 seconds. [59.220] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1 [59.221] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [59.222] task:btrfs state:D stack:0 pid:346822 ppid:1 flags:0x00004002 [59.222] Call Trace: [59.222] <TASK> [59.222] __schedule+0x392/0xa70 [59.222] schedule+0x5d/0xd0 [59.222] btrfs_scrub_cancel+0x91/0x100 [btrfs] [59.222] ? __pfx_autoremove_wake_function+0x10/0x10 [59.222] btrfs_commit_transaction+0x572/0xeb0 [btrfs] [59.223] ? start_transaction+0xcb/0x610 [btrfs] [59.223] prepare_to_relocate+0x111/0x1a0 [btrfs] [59.223] relocate_block_group+0x57/0x5d0 [btrfs] [59.223] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs] [59.223] btrfs_relocate_block_group+0x248/0x3c0 [btrfs] [59.224] ? __pfx_autoremove_wake_function+0x10/0x10 [59.224] btrfs_relocate_chunk+0x3b/0x150 [btrfs] [59.224] btrfs_balance+0x8ff/0x11d0 [btrfs] [59.224] ? __kmem_cache_alloc_node+0x14a/0x410 [59.224] btrfs_ioctl+0x2334/0x32c0 [btrfs] [59.225] ? mod_objcg_state+0xd2/0x360 [59.225] ? refill_obj_stock+0xb0/0x160 [59.225] ? seq_release+0x25/0x30 [59.225] ? __rseq_handle_notify_resume+0x3b5/0x4b0 [59.225] ? percpu_counter_add_batch+0x2e/0xa0 [59.225] ? __x64_sys_ioctl+0x88/0xc0 [59.225] __x64_sys_ioctl+0x88/0xc0 [59.225] do_syscall_64+0x38/0x90 [59.225] entry_SYSCALL_64_after_hwframe+0x72/0xdc [59.225] RIP: 0033:0x7f381a6ffe9b [59.225] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [59.225] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b [59.225] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003 [59.225] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000 [59.225] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423 [59.225] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148 [59.225] </TASK> What happens is the following: 1) A scrub is running, so fs_info->scrubs_running is 1; 2) Task A starts block group relocation, and at btrfs_relocate_chunk() it pauses scrub by calling btrfs_scrub_pause(). That increments fs_info->scrub_pause_req from 0 to 1 and waits for the scrub task to pause (for fs_info->scrubs_paused to be == to fs_info->scrubs_running); 3) The scrub task pauses at scrub_pause_off(), waiting for fs_info->scrub_pause_req to decrease to 0; 4) Task A then enters btrfs_relocate_block_group(), and down that call chain we start a transaction and then attempt to commit it; 5) When task A calls btrfs_commit_transaction(), it either will do the commit itself or wait for some other task that already started the commit of the transaction - it doesn't matter which case; 6) The transaction commit enters state TRANS_STATE_COMMIT_START; 7) An error happens during the transaction commit, like -ENOSPC when running delayed refs or delayed items for example; 8) This results in calling transaction.c:cleanup_transaction(), where we call btrfs_scrub_cancel(), incrementing fs_info->scrub_cancel_req from 0 to 1, and blocking this task waiting for fs_info->scrubs_running to decrease to 0; 9) From this point on, both the transaction commit and the scrub task hang forever: 1) The transaction commit is waiting for fs_info->scrubs_running to be decreased to 0; 2) The scrub task is at scrub_pause_off() waiting for fs_info->scrub_pause_req to decrease to 0 - so it can not proceed to stop the scrub and decrement fs_info->scrubs_running from 0 to 1. Therefore resulting in a deadlock. Fix this by having cleanup_transaction(), called if a transaction commit fails, not call btrfs_scrub_cancel() if relocation is in progress, and having btrfs_relocate_block_group() call btrfs_scrub_cancel() instead if the relocation failed and a transaction abort happened. This was triggered with btrfs/061 from fstests. Fixes: 55e3a601c81c ("btrfs: Fix data checksum error cause by replace with io-load.") CC: stable(a)vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 18329ebcb1cb..b8d5b1fa9a03 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -2035,7 +2035,20 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err) if (current->journal_info == trans) current->journal_info = NULL; - btrfs_scrub_cancel(fs_info); + + /* + * If relocation is running, we can't cancel scrub because that will + * result in a deadlock. Before relocating a block group, relocation + * pauses scrub, then starts and commits a transaction before unpausing + * scrub. If the transaction commit is being done by the relocation + * task or triggered by another task and the relocation task is waiting + * for the commit, and we end up here due to an error in the commit + * path, then calling btrfs_scrub_cancel() will deadlock, as we are + * asking for scrub to stop while having it asked to be paused higher + * above in relocation code. + */ + if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) + btrfs_scrub_cancel(fs_info); kmem_cache_free(btrfs_trans_handle_cachep, trans); } diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index ac0e8fb92fc8..c6d592870400 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3275,8 +3275,15 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) btrfs_scrub_pause(fs_info); ret = btrfs_relocate_block_group(fs_info, chunk_offset); btrfs_scrub_continue(fs_info); - if (ret) + if (ret) { + /* + * If we had a transaction abort, stop all running scrubs. + * See transaction.c:cleanup_transaction() why we do it here. + */ + if (BTRFS_FS_ERROR(fs_info)) + btrfs_scrub_cancel(fs_info); return ret; + } block_group = btrfs_lookup_block_group(fs_info, chunk_offset); if (!block_group)

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: ignore fiemap path cache when there are multiple paths" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 2280d425ba3599bdd85c41bd0ec8ba568f00c032 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040354-ramrod-papyrus-415b@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 2280d425ba35 ("btrfs: ignore fiemap path cache when there are multiple paths for a node") 73e339e6ab74 ("btrfs: cache sharedness of the last few data extents during fiemap") b629685803bc ("btrfs: remove roots ulist when checking data extent sharedness") 84a7949d4097 ("btrfs: move ulists to data extent sharedness check context") 61dbb952f0a5 ("btrfs: turn the backref sharedness check cache into a context object") ceb707da9ad9 ("btrfs: directly pass the inode to btrfs_is_data_extent_shared()") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2280d425ba3599bdd85c41bd0ec8ba568f00c032 Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Tue, 28 Mar 2023 10:45:20 +0100 Subject: [PATCH] btrfs: ignore fiemap path cache when there are multiple paths for a node During fiemap, when walking backreferences to determine if a b+tree node/leaf is shared, we may find a tree block (leaf or node) for which two parents were added to the references ulist. This happens if we get for example one direct ref (shared tree block ref) and one indirect ref (non-shared tree block ref) for the tree block at the current level, which can happen during relocation. In that case the fiemap path cache can not be used since it's meant for a single path, with one tree block at each possible level, so having multiple references for a tree block at any level may result in getting the level counter exceed BTRFS_MAX_LEVEL and eventually trigger the warning: WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL) at lookup_backref_shared_cache() and at store_backref_shared_cache(). This is harmless since the code ignores any level >= BTRFS_MAX_LEVEL, the warning is there just to catch any unexpected case like the one described above. However if a user finds this it may be scary and get reported. So just ignore the path cache once we find a tree block for which there are more than one reference, which is the less common case, and update the cache with the sharedness check result for all levels below the level for which we found multiple references. Reported-by: Jarno Pelkonen <jarno.pelkonen(a)gmail.com> Link: https://lore.kernel.org/linux-btrfs/CAKv8qLmDNAGJGCtsevxx_VZ_YOvvs1L83iEJkT… Fixes: 12a824dc67a6 ("btrfs: speedup checking for extent sharedness during fiemap") CC: stable(a)vger.kernel.org # 6.1+ Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 90e40d5ceccd..e54f0884802a 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1921,8 +1921,7 @@ int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, level = -1; ULIST_ITER_INIT(&uiter); while (1) { - bool is_shared; - bool cached; + const unsigned long prev_ref_count = ctx->refs.nnodes; walk_ctx.bytenr = bytenr; ret = find_parent_nodes(&walk_ctx, &shared); @@ -1940,21 +1939,36 @@ int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, ret = 0; /* - * If our data extent was not directly shared (without multiple - * reference items), than it might have a single reference item - * with a count > 1 for the same offset, which means there are 2 - * (or more) file extent items that point to the data extent - - * this happens when a file extent item needs to be split and - * then one item gets moved to another leaf due to a b+tree leaf - * split when inserting some item. In this case the file extent - * items may be located in different leaves and therefore some - * of the leaves may be referenced through shared subtrees while - * others are not. Since our extent buffer cache only works for - * a single path (by far the most common case and simpler to - * deal with), we can not use it if we have multiple leaves - * (which implies multiple paths). + * More than one extent buffer (bytenr) may have been added to + * the ctx->refs ulist, in which case we have to check multiple + * tree paths in case the first one is not shared, so we can not + * use the path cache which is made for a single path. Multiple + * extent buffers at the current level happen when: + * + * 1) level -1, the data extent: If our data extent was not + * directly shared (without multiple reference items), then + * it might have a single reference item with a count > 1 for + * the same offset, which means there are 2 (or more) file + * extent items that point to the data extent - this happens + * when a file extent item needs to be split and then one + * item gets moved to another leaf due to a b+tree leaf split + * when inserting some item. In this case the file extent + * items may be located in different leaves and therefore + * some of the leaves may be referenced through shared + * subtrees while others are not. Since our extent buffer + * cache only works for a single path (by far the most common + * case and simpler to deal with), we can not use it if we + * have multiple leaves (which implies multiple paths). + * + * 2) level >= 0, a tree node/leaf: We can have a mix of direct + * and indirect references on a b+tree node/leaf, so we have + * to check multiple paths, and the extent buffer (the + * current bytenr) may be shared or not. One example is + * during relocation as we may get a shared tree block ref + * (direct ref) and a non-shared tree block ref (indirect + * ref) for the same node/leaf. */ - if (level == -1 && ctx->refs.nnodes > 1) + if ((ctx->refs.nnodes - prev_ref_count) > 1) ctx->use_path_cache = false; if (level >= 0) @@ -1964,18 +1978,45 @@ int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, if (!node) break; bytenr = node->val; - level++; - cached = lookup_backref_shared_cache(ctx, root, bytenr, level, - &is_shared); - if (cached) { - ret = (is_shared ? 1 : 0); - break; + if (ctx->use_path_cache) { + bool is_shared; + bool cached; + + level++; + cached = lookup_backref_shared_cache(ctx, root, bytenr, + level, &is_shared); + if (cached) { + ret = (is_shared ? 1 : 0); + break; + } } shared.share_count = 0; shared.have_delayed_delete_refs = false; cond_resched(); } + /* + * If the path cache is disabled, then it means at some tree level we + * got multiple parents due to a mix of direct and indirect backrefs or + * multiple leaves with file extent items pointing to the same data + * extent. We have to invalidate the cache and cache only the sharedness + * result for the levels where we got only one node/reference. + */ + if (!ctx->use_path_cache) { + int i = 0; + + level--; + if (ret >= 0 && level >= 0) { + bytenr = ctx->path_cache_entries[level].bytenr; + ctx->use_path_cache = true; + store_backref_shared_cache(ctx, root, bytenr, level, ret); + i = level + 1; + } + + for ( ; i < BTRFS_MAX_LEVEL; i++) + ctx->path_cache_entries[i].bytenr = 0; + } + /* * Cache the sharedness result for the data extent if we know our inode * has more than 1 file extent item that refers to the data extent.

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: scan device in non-exclusive mode" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040340-happiest-next-a09c@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 50d281fc434c ("btrfs: scan device in non-exclusive mode") 12659251ca5d ("btrfs: implement log-structured superblock for ZONED mode") 5d1ab66c56fe ("btrfs: disallow space_cache in ZONED mode") b70f509774ad ("btrfs: check and enable ZONED mode") 5b316468983d ("btrfs: get zone information of zoned block devices") bacce86ae8a7 ("btrfs: drop unused argument step from btrfs_free_extra_devids") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 Mon Sep 17 00:00:00 2001 From: Anand Jain <anand.jain(a)oracle.com> Date: Thu, 23 Mar 2023 15:56:48 +0800 Subject: [PATCH] btrfs: scan device in non-exclusive mode This fixes mkfs/mount/check failures due to race with systemd-udevd scan. During the device scan initiated by systemd-udevd, other user space EXCL operations such as mkfs, mount, or check may get blocked and result in a "Device or resource busy" error. This is because the device scan process opens the device with the EXCL flag in the kernel. Two reports were received: - btrfs/179 test case, where the fsck command failed with the -EBUSY error - LTP pwritev03 test case, where mkfs.vfs failed with the -EBUSY error, when mkfs.vfs tried to overwrite old btrfs filesystem on the device. In both cases, fsck and mkfs (respectively) were racing with a systemd-udevd device scan, and systemd-udevd won, resulting in the -EBUSY error for fsck and mkfs. Reproducing the problem has been difficult because there is a very small window during which these userspace threads can race to acquire the exclusive device open. Even on the system where the problem was observed, the problem occurrences were anywhere between 10 to 400 iterations and chances of reproducing decreases with debug printk()s. However, an exclusive device open is unnecessary for the scan process, as there are no write operations on the device during scan. Furthermore, during the mount process, the superblock is re-read in the below function call chain: btrfs_mount_root btrfs_open_devices open_fs_devices btrfs_open_one_device btrfs_get_bdev_and_sb So, to fix this issue, removes the FMODE_EXCL flag from the scan operation, and add a comment. The case where mkfs may still write to the device and a scan is running, the btrfs signature is not written at that time so scan will not recognize such device. Reported-by: Sherry Yang <sherry.yang(a)oracle.com> Reported-by: kernel test robot <oliver.sang(a)intel.com> Link: https://lore.kernel.org/oe-lkp/202303170839.fdf23068-oliver.sang@intel.com CC: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6d0124b6e79e..ac0e8fb92fc8 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1366,8 +1366,17 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags, * So, we need to add a special mount option to scan for * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ - flags |= FMODE_EXCL; + /* + * Avoid using flag |= FMODE_EXCL here, as the systemd-udev may + * initiate the device scan which may race with the user's mount + * or mkfs command, resulting in failure. + * Since the device scan is solely for reading purposes, there is + * no need for FMODE_EXCL. Additionally, the devices are read again + * during the mount process. It is ok to get some inconsistent + * values temporarily, as the device paths of the fsid are the only + * required information for assembling the volume. + */ bdev = blkdev_get_by_path(path, flags, holder); if (IS_ERR(bdev)) return ERR_CAST(bdev);

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: scan device in non-exclusive mode" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040338-carving-ripping-8786@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 50d281fc434c ("btrfs: scan device in non-exclusive mode") 12659251ca5d ("btrfs: implement log-structured superblock for ZONED mode") 5d1ab66c56fe ("btrfs: disallow space_cache in ZONED mode") b70f509774ad ("btrfs: check and enable ZONED mode") 5b316468983d ("btrfs: get zone information of zoned block devices") bacce86ae8a7 ("btrfs: drop unused argument step from btrfs_free_extra_devids") 96c2e067ed3e ("btrfs: skip devices without magic signature when mounting") c3e1f96c37d0 ("btrfs: enumerate the type of exclusive operation in progress") 944d3f9fac61 ("btrfs: switch seed device to list api") c4989c2fd0eb ("btrfs: simplify setting/clearing fs_info to btrfs_fs_devices") 54eed6ae8d8e ("btrfs: make close_fs_devices return void") 3712ccb7f1cc ("btrfs: factor out loop logic from btrfs_free_extra_devids") dc0ab488d2cb ("btrfs: factor out reada loop in __reada_start_machine") adca4d945c8d ("btrfs: qgroup: remove ASYNC_COMMIT mechanism in favor of reserve retry-after-EDQUOT") 3092c68fc58c ("btrfs: sysfs: add bdi link to the fsid directory") 998a0671961f ("btrfs: include non-missing as a qualifier for the latest_bdev") 1ed802c972c6 ("btrfs: drop useless goto in open_fs_devices") b335eab890ed ("btrfs: make btrfs_read_disk_super return struct btrfs_disk_super") c4a816c67c39 ("btrfs: introduce chunk allocation policy") 9a8658e33d8f ("btrfs: open code trivial helper btrfs_header_fsid") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 Mon Sep 17 00:00:00 2001 From: Anand Jain <anand.jain(a)oracle.com> Date: Thu, 23 Mar 2023 15:56:48 +0800 Subject: [PATCH] btrfs: scan device in non-exclusive mode This fixes mkfs/mount/check failures due to race with systemd-udevd scan. During the device scan initiated by systemd-udevd, other user space EXCL operations such as mkfs, mount, or check may get blocked and result in a "Device or resource busy" error. This is because the device scan process opens the device with the EXCL flag in the kernel. Two reports were received: - btrfs/179 test case, where the fsck command failed with the -EBUSY error - LTP pwritev03 test case, where mkfs.vfs failed with the -EBUSY error, when mkfs.vfs tried to overwrite old btrfs filesystem on the device. In both cases, fsck and mkfs (respectively) were racing with a systemd-udevd device scan, and systemd-udevd won, resulting in the -EBUSY error for fsck and mkfs. Reproducing the problem has been difficult because there is a very small window during which these userspace threads can race to acquire the exclusive device open. Even on the system where the problem was observed, the problem occurrences were anywhere between 10 to 400 iterations and chances of reproducing decreases with debug printk()s. However, an exclusive device open is unnecessary for the scan process, as there are no write operations on the device during scan. Furthermore, during the mount process, the superblock is re-read in the below function call chain: btrfs_mount_root btrfs_open_devices open_fs_devices btrfs_open_one_device btrfs_get_bdev_and_sb So, to fix this issue, removes the FMODE_EXCL flag from the scan operation, and add a comment. The case where mkfs may still write to the device and a scan is running, the btrfs signature is not written at that time so scan will not recognize such device. Reported-by: Sherry Yang <sherry.yang(a)oracle.com> Reported-by: kernel test robot <oliver.sang(a)intel.com> Link: https://lore.kernel.org/oe-lkp/202303170839.fdf23068-oliver.sang@intel.com CC: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6d0124b6e79e..ac0e8fb92fc8 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1366,8 +1366,17 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags, * So, we need to add a special mount option to scan for * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ - flags |= FMODE_EXCL; + /* + * Avoid using flag |= FMODE_EXCL here, as the systemd-udev may + * initiate the device scan which may race with the user's mount + * or mkfs command, resulting in failure. + * Since the device scan is solely for reading purposes, there is + * no need for FMODE_EXCL. Additionally, the devices are read again + * during the mount process. It is ok to get some inconsistent + * values temporarily, as the device paths of the fsid are the only + * required information for assembling the volume. + */ bdev = blkdev_get_by_path(path, flags, holder); if (IS_ERR(bdev)) return ERR_CAST(bdev);

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: scan device in non-exclusive mode" failed to apply to 5.20-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.20-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.20.y git checkout FETCH_HEAD git cherry-pick -x 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040334-reproduce-granola-78a1@gregkh' --subject-prefix 'PATCH 5.20.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 Mon Sep 17 00:00:00 2001 From: Anand Jain <anand.jain(a)oracle.com> Date: Thu, 23 Mar 2023 15:56:48 +0800 Subject: [PATCH] btrfs: scan device in non-exclusive mode This fixes mkfs/mount/check failures due to race with systemd-udevd scan. During the device scan initiated by systemd-udevd, other user space EXCL operations such as mkfs, mount, or check may get blocked and result in a "Device or resource busy" error. This is because the device scan process opens the device with the EXCL flag in the kernel. Two reports were received: - btrfs/179 test case, where the fsck command failed with the -EBUSY error - LTP pwritev03 test case, where mkfs.vfs failed with the -EBUSY error, when mkfs.vfs tried to overwrite old btrfs filesystem on the device. In both cases, fsck and mkfs (respectively) were racing with a systemd-udevd device scan, and systemd-udevd won, resulting in the -EBUSY error for fsck and mkfs. Reproducing the problem has been difficult because there is a very small window during which these userspace threads can race to acquire the exclusive device open. Even on the system where the problem was observed, the problem occurrences were anywhere between 10 to 400 iterations and chances of reproducing decreases with debug printk()s. However, an exclusive device open is unnecessary for the scan process, as there are no write operations on the device during scan. Furthermore, during the mount process, the superblock is re-read in the below function call chain: btrfs_mount_root btrfs_open_devices open_fs_devices btrfs_open_one_device btrfs_get_bdev_and_sb So, to fix this issue, removes the FMODE_EXCL flag from the scan operation, and add a comment. The case where mkfs may still write to the device and a scan is running, the btrfs signature is not written at that time so scan will not recognize such device. Reported-by: Sherry Yang <sherry.yang(a)oracle.com> Reported-by: kernel test robot <oliver.sang(a)intel.com> Link: https://lore.kernel.org/oe-lkp/202303170839.fdf23068-oliver.sang@intel.com CC: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6d0124b6e79e..ac0e8fb92fc8 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1366,8 +1366,17 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags, * So, we need to add a special mount option to scan for * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ - flags |= FMODE_EXCL; + /* + * Avoid using flag |= FMODE_EXCL here, as the systemd-udev may + * initiate the device scan which may race with the user's mount + * or mkfs command, resulting in failure. + * Since the device scan is solely for reading purposes, there is + * no need for FMODE_EXCL. Additionally, the devices are read again + * during the mount process. It is ok to get some inconsistent + * values temporarily, as the device paths of the fsid are the only + * required information for assembling the volume. + */ bdev = blkdev_get_by_path(path, flags, holder); if (IS_ERR(bdev)) return ERR_CAST(bdev);

1 year, 8 months

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FAILED: patch "[PATCH] btrfs: scan device in non-exclusive mode" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2023040333-vanquish-wriggle-e007@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 50d281fc434c ("btrfs: scan device in non-exclusive mode") 12659251ca5d ("btrfs: implement log-structured superblock for ZONED mode") 5d1ab66c56fe ("btrfs: disallow space_cache in ZONED mode") b70f509774ad ("btrfs: check and enable ZONED mode") 5b316468983d ("btrfs: get zone information of zoned block devices") bacce86ae8a7 ("btrfs: drop unused argument step from btrfs_free_extra_devids") 96c2e067ed3e ("btrfs: skip devices without magic signature when mounting") c3e1f96c37d0 ("btrfs: enumerate the type of exclusive operation in progress") 944d3f9fac61 ("btrfs: switch seed device to list api") c4989c2fd0eb ("btrfs: simplify setting/clearing fs_info to btrfs_fs_devices") 54eed6ae8d8e ("btrfs: make close_fs_devices return void") 3712ccb7f1cc ("btrfs: factor out loop logic from btrfs_free_extra_devids") dc0ab488d2cb ("btrfs: factor out reada loop in __reada_start_machine") adca4d945c8d ("btrfs: qgroup: remove ASYNC_COMMIT mechanism in favor of reserve retry-after-EDQUOT") 3092c68fc58c ("btrfs: sysfs: add bdi link to the fsid directory") 998a0671961f ("btrfs: include non-missing as a qualifier for the latest_bdev") 1ed802c972c6 ("btrfs: drop useless goto in open_fs_devices") b335eab890ed ("btrfs: make btrfs_read_disk_super return struct btrfs_disk_super") c4a816c67c39 ("btrfs: introduce chunk allocation policy") 9a8658e33d8f ("btrfs: open code trivial helper btrfs_header_fsid") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 50d281fc434cb8e2497f5e70a309ccca6b1a09f0 Mon Sep 17 00:00:00 2001 From: Anand Jain <anand.jain(a)oracle.com> Date: Thu, 23 Mar 2023 15:56:48 +0800 Subject: [PATCH] btrfs: scan device in non-exclusive mode This fixes mkfs/mount/check failures due to race with systemd-udevd scan. During the device scan initiated by systemd-udevd, other user space EXCL operations such as mkfs, mount, or check may get blocked and result in a "Device or resource busy" error. This is because the device scan process opens the device with the EXCL flag in the kernel. Two reports were received: - btrfs/179 test case, where the fsck command failed with the -EBUSY error - LTP pwritev03 test case, where mkfs.vfs failed with the -EBUSY error, when mkfs.vfs tried to overwrite old btrfs filesystem on the device. In both cases, fsck and mkfs (respectively) were racing with a systemd-udevd device scan, and systemd-udevd won, resulting in the -EBUSY error for fsck and mkfs. Reproducing the problem has been difficult because there is a very small window during which these userspace threads can race to acquire the exclusive device open. Even on the system where the problem was observed, the problem occurrences were anywhere between 10 to 400 iterations and chances of reproducing decreases with debug printk()s. However, an exclusive device open is unnecessary for the scan process, as there are no write operations on the device during scan. Furthermore, during the mount process, the superblock is re-read in the below function call chain: btrfs_mount_root btrfs_open_devices open_fs_devices btrfs_open_one_device btrfs_get_bdev_and_sb So, to fix this issue, removes the FMODE_EXCL flag from the scan operation, and add a comment. The case where mkfs may still write to the device and a scan is running, the btrfs signature is not written at that time so scan will not recognize such device. Reported-by: Sherry Yang <sherry.yang(a)oracle.com> Reported-by: kernel test robot <oliver.sang(a)intel.com> Link: https://lore.kernel.org/oe-lkp/202303170839.fdf23068-oliver.sang@intel.com CC: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6d0124b6e79e..ac0e8fb92fc8 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1366,8 +1366,17 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags, * So, we need to add a special mount option to scan for * later supers, using BTRFS_SUPER_MIRROR_MAX instead */ - flags |= FMODE_EXCL; + /* + * Avoid using flag |= FMODE_EXCL here, as the systemd-udev may + * initiate the device scan which may race with the user's mount + * or mkfs command, resulting in failure. + * Since the device scan is solely for reading purposes, there is + * no need for FMODE_EXCL. Additionally, the devices are read again + * during the mount process. It is ok to get some inconsistent + * values temporarily, as the device paths of the fsid are the only + * required information for assembling the volume. + */ bdev = blkdev_get_by_path(path, flags, holder); if (IS_ERR(bdev)) return ERR_CAST(bdev);

1 year, 8 months

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Re: [PATCH] mm/swap: fix swap_info_struct race between swapoff and get_swap_pages()

by Rongwei Wang

On 4/3/23 12:10 PM, Matthew Wilcox wrote: > On Sun, Apr 02, 2023 at 06:19:20AM +0800, Rongwei Wang wrote: >> Without this modification, a core will wait (mostly) >> 'swap_info_struct->lock' when completing >> 'del_from_avail_list(p)'. Immediately, other cores >> soon calling 'add_to_avail_list()' to add the same >> object again when acquiring the lock that released >> by former. It's not the desired result but exists >> indeed. This case can be described as below: > This feels like a very verbose way of saying > > "The si->lock must be held when deleting the si from the > available list. Otherwise, another thread can re-add the > si to the available list, which can lead to memory corruption. > The only place we have found where this happens is in the > swapoff path." It looks better than mine. Sorry for my confusing description, it will be fixed in the next version. > >> +++ b/mm/swapfile.c >> @@ -2610,8 +2610,12 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) >> spin_unlock(&swap_lock); >> goto out_dput; >> } >> - del_from_avail_list(p); >> + /* >> + * Here lock is used to protect deleting and SWP_WRITEOK clearing >> + * can be seen concurrently. >> + */ > This comment isn't necessary. But I would add a lockdep assert inside > __del_from_avail_list() that p->lock is held. Thanks. Actually, I have this line in previous test version, but delete for saving one line of code. I will update here as you said. Thanks for your time. > >> spin_lock(&p->lock); >> + del_from_avail_list(p); >> if (p->prio < 0) { >> struct swap_info_struct *si = p; >> int nid; >> -- >> 2.27.0 >> >>

1 year, 8 months

1
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[PATCH 01/29] Revert "userfaultfd: don't fail on unrecognized features"

by Peter Xu

This is a proposal to revert commit 914eedcb9ba0ff53c33808. I found this when writting a simple UFFDIO_API test to be the first unit test in this set. Two things breaks with the commit: - UFFDIO_API check was lost and missing. According to man page, the kernel should reject ioctl(UFFDIO_API) if uffdio_api.api != 0xaa. This check is needed if the api version will be extended in the future, or user app won't be able to identify which is a new kernel. - Feature flags checks were removed, which means UFFDIO_API with a feature that does not exist will also succeed. According to the man page, we should (and it makes sense) to reject ioctl(UFFDIO_API) if unknown features passed in. Link: https://lore.kernel.org/r/20220722201513.1624158-1-axelrasmussen@google.com Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: linux-stable <stable(a)vger.kernel.org> Signed-off-by: Peter Xu <peterx(a)redhat.com> --- fs/userfaultfd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 8395605790f6..3b2a41c330e6 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1977,8 +1977,10 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, ret = -EFAULT; if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) goto out; - /* Ignore unsupported features (userspace built against newer kernel) */ - features = uffdio_api.features & UFFD_API_FEATURES; + features = uffdio_api.features; + ret = -EINVAL; + if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) + goto err_out; ret = -EPERM; if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE)) goto err_out; -- 2.39.1

1 year, 8 months

4
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WAITING FOR YOUR RESPONSE FOR MORE DISCUSSION.......

by Mrs. Rabi Juanni Marcus

Hello my beloved, good morning from here, how are you doing today? My name is Mrs. Rabi Juanni Marcus, I have something very important that i want to discuss with you.

1 year, 8 months

1
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Linux-stable-mirror April 2023