Eric Lee / smarc-ti-linux-kernel

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Commit 16f3a871c431a52d1461e88cf3c0d2e828366930

Authored by Konstantin Khlebnikov
Committed by Greg Kroah-Hartman
1 parent eec188a371
Exists in smarc-ti-linux-3.14.y and in 1 other branch processor-sdk-linux-01.00.00

cfq-iosched: handle failure of cfq group allocation 

commit 69abaffec7d47a083739b79e3066cb3730eba72e upstream.

Cfq_lookup_create_cfqg() allocates struct blkcg_gq using GFP_ATOMIC.
In cfq_find_alloc_queue() possible allocation failure is not handled.
As a result kernel oopses on NULL pointer dereference when
cfq_link_cfqq_cfqg() calls cfqg_get() for NULL pointer.

Bug was introduced in v3.5 in commit cd1604fab4f9 ("blkcg: factor
out blkio_group creation"). Prior to that commit cfq group lookup
had returned pointer to root group as fallback.

This patch handles this error using existing fallback oom_cfqq.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Fixes: cd1604fab4f9 ("blkcg: factor out blkio_group creation")
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 6 additions and 1 deletions Side-by-side Diff

... ... @@ -3585,6 +3585,11 @@
3585 3585  
3586 3586 blkcg = bio_blkcg(bio);
3587 3587 cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
  3588 + if (!cfqg) {
  3589 + cfqq = &cfqd->oom_cfqq;
  3590 + goto out;
  3591 + }
  3592 +
3588 3593 cfqq = cic_to_cfqq(cic, is_sync);
3589 3594  
3590 3595 /*
... ... @@ -3621,7 +3626,7 @@
3621 3626 } else
3622 3627 cfqq = &cfqd->oom_cfqq;
3623 3628 }
3624   -
  3629 +out:
3625 3630 if (new_cfqq)
3626 3631 kmem_cache_free(cfq_pool, new_cfqq);
3627 3632