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From: Ritesh Harjani <>
	Ritesh Harjani <>,
	Shivaprasad G Bhat <>,
	Anju T Sudhakar <>
Subject: [RESEND PATCH 1/1] block: Set same_page to false in __bio_try_merge_page if ret is false
Date: Wed,  9 Sep 2020 08:44:25 +0530	[thread overview]
Message-ID: <> (raw)

If we hit the UINT_MAX limit of bio->bi_iter.bi_size and so we are anyway
not merging this page in this bio, then it make sense to make same_page
also as false before returning.

Without this patch, we hit below WARNING in iomap.
This mostly happens with very large memory system and / or after tweaking
vm dirty threshold params to delay writeback of dirty data.

WARNING: CPU: 18 PID: 5130 at fs/iomap/buffered-io.c:74 iomap_page_release+0x120/0x150
 CPU: 18 PID: 5130 Comm: fio Kdump: loaded Tainted: G        W         5.8.0-rc3 #6
 Call Trace:
  __remove_mapping+0x154/0x320 (unreliable)
  xfs_file_fadvise+0x2c/0xe0 [xfs]

Fixes: cc90bc68422 ("block: fix "check bi_size overflow before merge"")
Suggested-by: Christoph Hellwig <>
Reported-by: Shivaprasad G Bhat <>
Signed-off-by: Anju T Sudhakar <>
Signed-off-by: Ritesh Harjani <>
RESEND: added "fixes" tag

 block/bio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index a7366c02c9b5..675ecd81047b 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -877,8 +877,10 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
 		struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
 		if (page_is_mergeable(bv, page, len, off, same_page)) {
-			if (bio->bi_iter.bi_size > UINT_MAX - len)
+			if (bio->bi_iter.bi_size > UINT_MAX - len) {
+				*same_page = false;
 				return false;
+			}
 			bv->bv_len += len;
 			bio->bi_iter.bi_size += len;
 			return true;

             reply	other threads:[~2020-09-09  3:15 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-09  3:14 Ritesh Harjani [this message]
2020-09-09  3:36 ` Ming Lei
2020-09-09  6:01 ` Christoph Hellwig
2020-09-09 14:19 ` Jens Axboe

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