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md/raid1,raid10: fix error-path detection with md_cloned_bio()

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Detect the error path using md_cloned_bio() instead of relying
on r1_bio in raid1 or r10_bio->read_slot in raid10, which may be
NULL or -1 after splitting and resubmitting a failed bio.

As a result, the error path may not be recognized and memory
allocations can incorrectly use GFP_NOIO instead of
(GFP_NOIO | __GFP_HIGH), which can lead to a deadlock under
memory pressure.

Fixes: 689389a06c ("md/raid1: simplify handle_read_error().")
Fixes: 545250f248 ("md/raid10: simplify handle_read_error()")
Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Reviewed-by: Xiao Ni <xiao@kernel.org>
Link: https://patch.msgid.link/20260501114652.590037-3-abd.masalkhi@gmail.com
Signed-off-by: Yu Kuai <yukuai@fygo.io>
This commit is contained in:
Abd-Alrhman Masalkhi 2026-05-01 13:46:50 +02:00 committed by Yu Kuai
parent 7b15c24f80
commit 811545e092
2 changed files with 24 additions and 9 deletions
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13
drivers/md/raid1.c
View File

@ -1343,11 +1343,18 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
bool r1bio_existed = !!r1_bio;
/*
* If r1_bio is set, we are blocking the raid1d thread
* so there is a tiny risk of deadlock. So ask for
* An md cloned bio indicates we are in the error path.
* This is more reliable than checking r1_bio, which might
* be NULL even in the error path if a failed bio was split.
*/
bool err_path = md_cloned_bio(mddev, bio);
/*
* If we are in the error path, we are blocking the raid1d
* thread so there is a tiny risk of deadlock. So ask for
* emergency memory if needed.
*/
gfp_t gfp = r1_bio ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO;
gfp_t gfp = err_path ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO;
/*
* Still need barrier for READ in case that whole

20
drivers/md/raid10.c
View File

@ -1155,7 +1155,20 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
char b[BDEVNAME_SIZE];
int slot = r10_bio->read_slot;
struct md_rdev *err_rdev = NULL;
gfp_t gfp = GFP_NOIO;
/*
* An md cloned bio indicates we are in the error path.
* This is more reliable than checking slot, which might
* be -1 even in the error path if a failed bio was split.
*/
bool err_path = md_cloned_bio(mddev, bio);
/*
* If we are in the error path, we are blocking the raid10d
* thread so there is a tiny risk of deadlock. So ask for
* emergency memory if needed.
*/
gfp_t gfp = err_path ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO;
if (slot >= 0 && r10_bio->devs[slot].rdev) {
/*
@ -1166,11 +1179,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
* we lose the device name in error messages.
*/
int disk;
/*
* As we are blocking raid10, it is a little safer to
* use __GFP_HIGH.
*/
gfp = GFP_NOIO | __GFP_HIGH;
disk = r10_bio->devs[slot].devnum;
err_rdev = conf->mirrors[disk].rdev;