iMX/i2som-imx-linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fix unbalanced page refcounting in bio_map_user_iov

Browse Source 
commit 95d78c28b5 upstream.

bio_map_user_iov and bio_unmap_user do unbalanced pages refcounting if
IO vector has small consecutive buffers belonging to the same page.
bio_add_pc_page merges them into one, but the page reference is never
dropped.

Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Vitaly Mayatskikh
2017-09-22 01:18:39 -04:00
committed by Ben Hutchings
parent 90d8668e4a
commit 9ff5d8fe36
1 changed files with 8 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
fs/bio.c
View File

@ -1027,6 +1027,7 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
offset = uaddr & ~PAGE_MASK;
for (j = cur_page; j < page_limit; j++) {
unsigned int bytes = PAGE_SIZE - offset;
unsigned short prev_bi_vcnt = bio->bi_vcnt;
if (len <= 0)
break;
@ -1041,6 +1042,13 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
bytes)
break;
/*
* check if vector was merged with previous
* drop page reference if needed
*/
if (bio->bi_vcnt == prev_bi_vcnt)
put_page(pages[j]);
len -= bytes;
offset = 0;
}