Re: [PATCH 1/2] md/raid5: Remove unnecessary bio_put() in raid5_read_one_chunk()
From: Paul Menzel <hidden>
Date: 2022-09-05 06:07:29
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Dear Logan, dear David, Thank you for the patch. Am 02.09.22 um 19:16 schrieb Logan Gunthorpe:
From: David Sloan <redacted>
When running chunk-sized reads on disks with badblocks duplicate bio
free/puts are observed:
=============================================================================
BUG bio-200 (Not tainted): Object already free
-----------------------------------------------------------------------------
Allocated in mempool_alloc_slab+0x17/0x20 age=3 cpu=2 pid=7504
__slab_alloc.constprop.0+0x5a/0xb0[…]
The double free is caused by an unnecessary bio_put() in the
if(is_badblock(...)) error path in raid5_read_one_chunk().
The error path was moved ahead of bio_alloc_clone() in c82aa1b76787c
("md/raid5: move checking badblock before clone bio in
raid5_read_one_chunk"). The previous code checked and freed align_bio
which required a bio_put. After he move that is no longer needed as*t*he move
raid_bio is returned to the control of the common io path which
performs its own endio resulting in a double free on bad device blocks.
Fixes: c82aa1b76787c ("md/raid5: move checking badblock before clone bio in raid5_read_one_chunk")This commit was added to Linux in v5.14-rc1, so it’s not a recent commit – or I misunderstood the cover letter. Kind regards, Paul
quoted hunk ↗ jump to hunk
Signed-off-by: David Sloan <redacted> [logang@deltatee.com: minor rewording of commit message] Signed-off-by: Logan Gunthorpe <logang@deltatee.com> --- drivers/md/raid5.c | 1 - 1 file changed, 1 deletion(-)diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 4e6d865a6456..734f92e75f85 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c@@ -5538,7 +5538,6 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio) if (is_badblock(rdev, sector, bio_sectors(raid_bio), &first_bad, &bad_sectors)) { - bio_put(raid_bio); rdev_dec_pending(rdev, mddev); return 0; }