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block: Set same_page to false in __bio_try_merge_page if ret is false
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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)
  iomap_releasepage+0x80/0x180
  try_to_release_page+0x94/0xe0
  invalidate_inode_page+0xc8/0x110
  invalidate_mapping_pages+0x1dc/0x540
  generic_fadvise+0x3c8/0x450
  xfs_file_fadvise+0x2c/0xe0 [xfs]
  vfs_fadvise+0x3c/0x60
  ksys_fadvise64_64+0x68/0xe0
  sys_fadvise64+0x28/0x40
  system_call_exception+0xf8/0x1c0
  system_call_common+0xf0/0x278

Fixes: cc90bc6 ("block: fix "check bi_size overflow before merge"")
Reported-by: Shivaprasad G Bhat <[email protected]>
Suggested-by: Christoph Hellwig <[email protected]>
Signed-off-by: Anju T Sudhakar <[email protected]>
Signed-off-by: Ritesh Harjani <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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riteshharjani authored and axboe committed Sep 9, 2020
1 parent e8a8a18 commit 2cd896a
Showing 1 changed file with 3 additions and 1 deletion.
4 changes: 3 additions & 1 deletion block/bio.c
Original file line number Diff line number Diff line change
Expand Up @@ -879,8 +879,10 @@ 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;
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