On Fri, 26 Apr 2024 19:29:38 +0800 Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
> See commit f2c817bed58d ("mm: use memalloc_nofs_save in readahead
> path"), ensure that page_cache_ra_order() do not attempt to reclaim
> file-backed pages too, or it leads to a deadlock, found issue when
> test ext4 large folio.
>
> INFO: task DataXceiver for:7494 blocked for more than 120 seconds.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:DataXceiver for state:D stack:0 pid:7494 ppid:1 flags:0x00000200
> Call trace:
> __switch_to+0x14c/0x240
> __schedule+0x82c/0xdd0
> schedule+0x58/0xf0
> io_schedule+0x24/0xa0
> __folio_lock+0x130/0x300
> migrate_pages_batch+0x378/0x918
> migrate_pages+0x350/0x700
> compact_zone+0x63c/0xb38
> compact_zone_order+0xc0/0x118
> try_to_compact_pages+0xb0/0x280
> __alloc_pages_direct_compact+0x98/0x248
> __alloc_pages+0x510/0x1110
> alloc_pages+0x9c/0x130
> folio_alloc+0x20/0x78
> filemap_alloc_folio+0x8c/0x1b0
> page_cache_ra_order+0x174/0x308
> ondemand_readahead+0x1c8/0x2b8
> page_cache_async_ra+0x68/0xb8
> filemap_readahead.isra.0+0x64/0xa8
> filemap_get_pages+0x3fc/0x5b0
> filemap_splice_read+0xf4/0x280
> ext4_file_splice_read+0x2c/0x48 [ext4]
> vfs_splice_read.part.0+0xa8/0x118
> splice_direct_to_actor+0xbc/0x288
> do_splice_direct+0x9c/0x108
> do_sendfile+0x328/0x468
> __arm64_sys_sendfile64+0x8c/0x148
> invoke_syscall+0x4c/0x118
> el0_svc_common.constprop.0+0xc8/0xf0
> do_el0_svc+0x24/0x38
> el0_svc+0x4c/0x1f8
> el0t_64_sync_handler+0xc0/0xc8
> el0t_64_sync+0x188/0x190
>
> Cc: zhangyi (F) <yi.zhang@xxxxxxxxxx>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
I'm thinking
Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
Cc: stable
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -494,6 +494,7 @@ void page_cache_ra_order(struct readahead_control *ractl,
> pgoff_t index = readahead_index(ractl);
> pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT;
> pgoff_t mark = index + ra->size - ra->async_size;
> + unsigned int nofs;
> int err = 0;
> gfp_t gfp = readahead_gfp_mask(mapping);
>
> @@ -508,6 +509,8 @@ void page_cache_ra_order(struct readahead_control *ractl,
> new_order = min_t(unsigned int, new_order, ilog2(ra->size));
> }
>
> + /* See comment in page_cache_ra_unbounded() */
> + nofs = memalloc_nofs_save();
> filemap_invalidate_lock_shared(mapping);
> while (index <= limit) {
> unsigned int order = new_order;
> @@ -531,6 +534,7 @@ void page_cache_ra_order(struct readahead_control *ractl,
>
> read_pages(ractl);
> filemap_invalidate_unlock_shared(mapping);
> + memalloc_nofs_restore(nofs);
>
> /*
> * If there were already pages in the page cache, then we may have
> --
> 2.41.0
