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>
---
mm/readahead.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/readahead.c b/mm/readahead.c
index 63d6000103f0..c1b23989d9ca 100644
--- 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
