This patch turned out to be wrong and was reverted. Please drop this patch.
commit 947b7ac135b16aa60f9141ff72bd494eda0edb5e Author: Jens Axboe axboe@kernel.dk Date: Sun Jan 27 06:35:28 2019 -0700
Revert "block: cover another queue enter recursion via BIO_QUEUE_ENTERED"
We can't touch a bio after ->make_request_fn(), for all we know it could already have been completed by the time this function returns.
This reverts commit 698cef173983b086977e633e46476e0f925ca01e.
Reported-by: syzbot+4df6ca820108fd248943@syzkaller.appspotmail.com Signed-off-by: Jens Axboe axboe@kernel.dk
From: Ming Lei ming.lei@redhat.com
[ Upstream commit 698cef173983b086977e633e46476e0f925ca01e ]
Except for blk_queue_split(), bio_split() is used for splitting bio too, then the remained bio is often resubmit to queue via generic_make_request(). So the same queue enter recursion exits in this case too. Unfortunatley commit cd4a4ae4683dc2 doesn't help this case.
This patch covers the above case by setting BIO_QUEUE_ENTERED before calling q->make_request_fn.
In theory the per-bio flag is used to simulate one stack variable, it is just fine to clear it after q->make_request_fn is returned. Especially the same bio can't be submitted from another context.
Fixes: cd4a4ae4683dc2 ("block: don't use blocking queue entered for recursive bio submits") Cc: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: NeilBrown neilb@suse.com Reviewed-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org
block/blk-core.c | 11 +++++++++++ block/blk-merge.c | 10 ---------- 2 files changed, 11 insertions(+), 10 deletions(-)