Fwd: btrfs: OOM in split_item().

[Qu Wenruo <wqu@suse.com>]

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Forwarded for archive purposes, as patchcheck requires a link: tag 
following reported-by: tag.

Meanwhile the original report is only a private mail to me.

-------- 转发的消息 --------
主题: 	btrfs: OOM in split_item().
日期: 	Mon, 07 Sep 2026 20:10:56 +0000
发件人: 	xavierbachmeyer182 <xavierbachmeyer182@protonmail.com>
收件人: 	wqu@suse.com <wqu@suse.com>



Hello.

Attached is a kernel log entry showing a strange out of memory issue 
that rarely seems to happen.
It's kind of annoying and makes me wish GFP_NOFS would go the way of the 
dinosaur.

Thanks and have a good day / evening.


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[5558615.041527] kworker/u69:8: page allocation failure: order:4, mode:0x40c40(GFP_NOFS|__GFP_COMP), nodemask=(null)
[5558615.041540] CPU: 3 UID: 0 PID: 1154528 Comm: kworker/u69:8 Not tainted 7.0.2 #1 PREEMPTLAZY 
[5558615.041544] Workqueue: events_unbound btrfs_async_reclaim_metadata_space
[5558615.041550] Call Trace:
[5558615.041553]  <TASK>
[5558615.041554]  dump_stack_lvl+0x47/0x60
[5558615.041558]  warn_alloc.cold+0x67/0xec
[5558615.041561]  __alloc_pages_slowpath.constprop.0+0x9bf/0xed0
[5558615.041565]  __alloc_frozen_pages_noprof+0x1ac/0x1c0
[5558615.041567]  ___kmalloc_large_node+0x9d/0xc0
[5558615.041569]  __kmalloc_noprof+0x17b/0x1f0
[5558615.041571]  split_item+0x9e/0x2e0
[5558615.041574]  ? memset_extent_buffer+0xd3/0x120
[5558615.041576]  btrfs_del_csums+0x285/0x400
[5558615.041578]  ? release_extent_buffer+0x3c/0x100
[5558615.041579]  ? btrfs_csum_root+0x94/0xc0
[5558615.041581]  __btrfs_free_extent.isra.0+0x6de/0x12b0
[5558615.041583]  __btrfs_run_delayed_refs+0x522/0x10c0
[5558615.041586]  ? __write_extent_buffer+0x13d/0x1d0
[5558615.041587]  ? btrfs_qgroup_convert_reserved_meta+0x20/0x290
[5558615.041589]  ? btrfs_block_rsv_release+0x153/0x1f0
[5558615.041591]  ? __btrfs_update_delayed_inode+0xcb/0x450
[5558615.041593]  btrfs_run_delayed_refs+0x4d/0x1d0
[5558615.041595]  flush_space+0x34d/0x4e0
[5558615.041597]  ? btrfs_reduce_alloc_profile+0xa2/0x1a0
[5558615.041599]  ? calc_available_free_space.isra.0+0x58/0x90
[5558615.041601]  ? btrfs_calc_reclaim_metadata_size+0x20/0x60
[5558615.041603]  do_async_reclaim_metadata_space+0x89/0x1d0
[5558615.041605]  ? mempool_free+0x3b/0x60
[5558615.041609]  btrfs_async_reclaim_metadata_space+0x44/0x60
[5558615.041611]  process_one_work+0x145/0x230
[5558615.041614]  worker_thread+0x185/0x2e0
[5558615.041616]  ? rescuer_thread+0x4a0/0x4a0
[5558615.041617]  kthread+0xca/0x100
[5558615.041619]  ? kthreads_online_cpu+0x10/0x10
[5558615.041620]  ret_from_fork+0x14e/0x200
[5558615.041623]  ? kthreads_online_cpu+0x10/0x10
[5558615.041624]  ? kthreads_online_cpu+0x10/0x10
[5558615.041625]  ret_from_fork_asm+0x11/0x20
[5558615.041628]  </TASK>
[5558615.041629] Mem-Info:
[5558615.041635] active_anon:22695 inactive_anon:822896 isolated_anon:0
                  active_file:3274307 inactive_file:2571939 isolated_file:0
                  unevictable:582 dirty:20975 writeback:161089
                  slab_reclaimable:1024567 slab_unreclaimable:61165
                  mapped:153706 shmem:48899 pagetables:8758
                  sec_pagetables:0 bounce:0
                  kernel_misc_reclaimable:0
                  free:254495 free_pcp:104 free_cma:0
[5558615.041641] Node 0 active_anon:90780kB inactive_anon:3291584kB active_file:13097228kB inactive_file:10287756kB unevictable:2328kB isolated(anon):0kB isolated(file):0kB mapped:614824kB dirty:83900kB writeback:644356kB shmem:195596kB kernel_stack:19392kB pagetables:35032kB sec_pagetables:0kB all_unreclaimable? no Balloon:0kB
[5558615.041645] DMA32 free:255048kB boost:8192kB min:10336kB low:13400kB high:16464kB reserved_highatomic:4096KB free_highatomic:3976KB active_anon:13720kB inactive_anon:91944kB active_file:924484kB inactive_file:674012kB unevictable:244kB writepending:150372kB zspages:0kB present:3329364kB managed:3084408kB mlocked:244kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
[5558615.041650] lowmem_reserve[]: 0 28864 28864 28864
[5558615.041654] Normal free:762932kB boost:65536kB min:86232kB low:115788kB high:145344kB reserved_highatomic:4096KB free_highatomic:4096KB active_anon:76968kB inactive_anon:3199640kB active_file:12172576kB inactive_file:9614396kB unevictable:2084kB writepending:578116kB zspages:0kB present:30133760kB managed:29556920kB mlocked:2084kB bounce:0kB free_pcp:416kB local_pcp:0kB free_cma:0kB
[5558615.041659] lowmem_reserve[]: 0 0 0 0
[5558615.041661] DMA32: 20347*4kB (UME) 12098*8kB (UMEH) 3960*16kB (UMEH) 293*32kB (MEH) 7*64kB (H) 1*128kB (H) 4*256kB (H) 0*512kB 2*1024kB (H) 0*2048kB 0*4096kB = 254556kB
[5558615.041675] Normal: 116705*4kB (UME) 28108*8kB (UME) 3330*16kB (UME) 379*32kB (UME) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 1*4096kB (H) = 761188kB
[5558615.041686] 5801327 total pagecache pages
[5558615.041687] 8365781 pages RAM
[5558615.041688] 0 pages HighMem/MovableOnly
[5558615.041689] 205449 pages reserved
[5558615.041690] 0 pages hwpoisoned
[5558615.041691] BTRFS error (device dm-3 state A): Transaction aborted (error -12)
[5558615.041696] BTRFS: error (device dm-3 state A) in btrfs_del_csums:1053: errno=-12 Out of memory
[5558615.041698] BTRFS info (device dm-3 state EA): forced readonly
[5558615.041701] BTRFS: error (device dm-3 state EA) in do_free_extent_accounting:3168: errno=-12 Out of memory
[5558615.041704] BTRFS error (device dm-3 state EA): failed to run delayed ref for logical 1202913873920 num_bytes 274432 type 184 action 2 ref_mod 1: -12
[5558615.041708] BTRFS: error (device dm-3 state EA) in btrfs_run_delayed_refs:2247: errno=-12 Out of memory