On 07/05/24 3:06 pm, Ritesh Harjani (IBM) wrote:
An async dio write to a sparse file can generate a lot of extents and when we unlink this file (using rm), the kernel can be busy in umapping and freeing those extents as part of transaction processing. Similarly xfs reflink remapping path can also iterate over a million extent entries in xfs_reflink_remap_blocks(). Since we can busy loop in these two functions, so let's add cond_resched() to avoid softlockup messages like these. watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [kworker/1:0:82435] CPU: 1 PID: 82435 Comm: kworker/1:0 Tainted: G S L 6.9.0-rc5-0-default #1 Workqueue: xfs-inodegc/sda2 xfs_inodegc_worker NIP [c000000000beea10] xfs_extent_busy_trim+0x100/0x290 LR [c000000000bee958] xfs_extent_busy_trim+0x48/0x290 Call Trace: xfs_alloc_get_rec+0x54/0x1b0 (unreliable) xfs_alloc_compute_aligned+0x5c/0x144 xfs_alloc_ag_vextent_size+0x238/0x8d4 xfs_alloc_fix_freelist+0x540/0x694 xfs_free_extent_fix_freelist+0x84/0xe0 __xfs_free_extent+0x74/0x1ec xfs_extent_free_finish_item+0xcc/0x214 xfs_defer_finish_one+0x194/0x388 xfs_defer_finish_noroll+0x1b4/0x5c8 xfs_defer_finish+0x2c/0xc4 xfs_bunmapi_range+0xa4/0x100 xfs_itruncate_extents_flags+0x1b8/0x2f4 xfs_inactive_truncate+0xe0/0x124 xfs_inactive+0x30c/0x3e0 xfs_inodegc_worker+0x140/0x234 process_scheduled_works+0x240/0x57c worker_thread+0x198/0x468 kthread+0x138/0x140 start_kernel_thread+0x14/0x18 run fstests generic/175 at 2024-02-02 04:40:21 [ C17] watchdog: BUG: soft lockup - CPU#17 stuck for 23s! [xfs_io:7679] watchdog: BUG: soft lockup - CPU#17 stuck for 23s! [xfs_io:7679] CPU: 17 PID: 7679 Comm: xfs_io Kdump: loaded Tainted: G X 6.4.0 NIP [c008000005e3ec94] xfs_rmapbt_diff_two_keys+0x54/0xe0 [xfs] LR [c008000005e08798] xfs_btree_get_leaf_keys+0x110/0x1e0 [xfs] Call Trace: 0xc000000014107c00 (unreliable) __xfs_btree_updkeys+0x8c/0x2c0 [xfs] xfs_btree_update_keys+0x150/0x170 [xfs] xfs_btree_lshift+0x534/0x660 [xfs] xfs_btree_make_block_unfull+0x19c/0x240 [xfs] xfs_btree_insrec+0x4e4/0x630 [xfs] xfs_btree_insert+0x104/0x2d0 [xfs] xfs_rmap_insert+0xc4/0x260 [xfs] xfs_rmap_map_shared+0x228/0x630 [xfs] xfs_rmap_finish_one+0x2d4/0x350 [xfs] xfs_rmap_update_finish_item+0x44/0xc0 [xfs] xfs_defer_finish_noroll+0x2e4/0x740 [xfs] __xfs_trans_commit+0x1f4/0x400 [xfs] xfs_reflink_remap_extent+0x2d8/0x650 [xfs] xfs_reflink_remap_blocks+0x154/0x320 [xfs] xfs_file_remap_range+0x138/0x3a0 [xfs] do_clone_file_range+0x11c/0x2f0 vfs_clone_file_range+0x60/0x1c0 ioctl_file_clone+0x78/0x140 sys_ioctl+0x934/0x1270 system_call_exception+0x158/0x320 system_call_vectored_common+0x15c/0x2ec Cc: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
Thanks for the fix patch. I have tested it on a power machine, and it resolves the soft lockup issue. Tested-by: Disha Goel<disgoel@xxxxxxxxxxxxx>
--- fs/xfs/libxfs/xfs_bmap.c | 1 + fs/xfs/xfs_reflink.c | 1 + 2 files changed, 2 insertions(+) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 656c95a22f2e..44d5381bc66f 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -6354,6 +6354,7 @@ xfs_bunmapi_range( error = xfs_defer_finish(tpp); if (error) goto out; + cond_resched(); } out: return error; diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 7da0e8f961d3..5f26a608bc09 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1417,6 +1417,7 @@ xfs_reflink_remap_blocks( destoff += imap.br_blockcount; len -= imap.br_blockcount; remapped_len += imap.br_blockcount; + cond_resched(); } if (error) -- 2.44.0
