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Subject[PATCH 3.12 033/103] md/raid1: r1buf_pool_alloc: free allocate pages when subsequent allocation fails.
Date
From: NeilBrown <neilb@suse.de>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit da1aab3dca9aa88ae34ca392470b8943159e25fe upstream.

When performing a user-request check/repair (MD_RECOVERY_REQUEST is set)
on a raid1, we allocate multiple bios each with their own set of pages.

If the page allocations for one bio fails, we currently do *not* free
the pages allocated for the previous bios, nor do we free the bio itself.

This patch frees all the already-allocate pages, and makes sure that
all the bios are freed as well.

This bug can cause a memory leak which can ultimately OOM a machine.
It was introduced in 3.10-rc1.

Fixes: a07876064a0b73ab5ef1ebcf14b1cf0231c07858
Cc: Kent Overstreet <koverstreet@google.com>
Reported-by: Russell King - ARM Linux <linux@arm.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/md/raid1.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6edc2db428e9..66c4aee20c72 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -94,6 +94,7 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
struct pool_info *pi = data;
struct r1bio *r1_bio;
struct bio *bio;
+ int need_pages;
int i, j;

r1_bio = r1bio_pool_alloc(gfp_flags, pi);
@@ -116,15 +117,15 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
* RESYNC_PAGES for each bio.
*/
if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
- j = pi->raid_disks;
+ need_pages = pi->raid_disks;
else
- j = 1;
- while(j--) {
+ need_pages = 1;
+ for (j = 0; j < need_pages; j++) {
bio = r1_bio->bios[j];
bio->bi_vcnt = RESYNC_PAGES;

if (bio_alloc_pages(bio, gfp_flags))
- goto out_free_bio;
+ goto out_free_pages;
}
/* If not user-requests, copy the page pointers to all bios */
if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
@@ -138,6 +139,14 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)

return r1_bio;

+out_free_pages:
+ while (--j >= 0) {
+ struct bio_vec *bv;
+
+ bio_for_each_segment_all(bv, r1_bio->bios[j], i)
+ __free_page(bv->bv_page);
+ }
+
out_free_bio:
while (++j < pi->raid_disks)
bio_put(r1_bio->bios[j]);
--
1.9.3


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