FAILED: patch "[PATCH] dm: fix bio splitting and its bio completion order for" failed to apply to 5.4-stable tree
The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4a40df8af7d3..d948cd522431 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1724,23 +1724,6 @@ static blk_qc_t __process_bio(struct mapped_device *md, struct dm_table *map, return ret; }
-static void dm_queue_split(struct mapped_device *md, struct dm_target *ti, struct bio **bio) -{ - unsigned len, sector_count; - - sector_count = bio_sectors(*bio); - len = min_t(sector_t, max_io_len((*bio)->bi_iter.bi_sector, ti), sector_count); - - if (sector_count > len) { - struct bio *split = bio_split(*bio, len, GFP_NOIO, &md->queue->bio_split); - - bio_chain(split, *bio); - trace_block_split(md->queue, split, (*bio)->bi_iter.bi_sector); - submit_bio_noacct(*bio); - *bio = split; - } -} - static blk_qc_t dm_process_bio(struct mapped_device *md, struct dm_table *map, struct bio *bio) { @@ -1768,14 +1751,12 @@ static blk_qc_t dm_process_bio(struct mapped_device *md, if (current->bio_list) { if (is_abnormal_io(bio)) blk_queue_split(&bio); - else - dm_queue_split(md, ti, &bio); + /* regular IO is split by __split_and_process_bio */ }
if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED) return __process_bio(md, map, bio, ti); - else - return __split_and_process_bio(md, map, bio); + return __split_and_process_bio(md, map, bio); }
static blk_qc_t dm_submit_bio(struct bio *bio)
This backport applies (with mild offset) to both v5.4.67 and v5.8.11:
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
--- a/drivers/md/dm.c 2020-09-21 18:46:16.000000000 -0400 +++ b/drivers/md/dm.c 2020-09-21 18:33:21.000000000 -0400 @@ -1727,23 +1727,6 @@ return ret; }
-static void dm_queue_split(struct mapped_device *md, struct dm_target *ti, struct bio **bio) -{ - unsigned len, sector_count; - - sector_count = bio_sectors(*bio); - len = min_t(sector_t, max_io_len((*bio)->bi_iter.bi_sector, ti), sector_count); - - if (sector_count > len) { - struct bio *split = bio_split(*bio, len, GFP_NOIO, &md->queue->bio_split); - - bio_chain(split, *bio); - trace_block_split(md->queue, split, (*bio)->bi_iter.bi_sector); - generic_make_request(*bio); - *bio = split; - } -} - static blk_qc_t dm_process_bio(struct mapped_device *md, struct dm_table *map, struct bio *bio) { @@ -1773,14 +1756,12 @@ if (current->bio_list) { if (is_abnormal_io(bio)) blk_queue_split(md->queue, &bio); - else - dm_queue_split(md, ti, &bio); + /* regular IO is split by __split_and_process_bio */ }
if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED) return __process_bio(md, map, bio, ti); - else - return __split_and_process_bio(md, map, bio); + return __split_and_process_bio(md, map, bio); }
static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
On Mon, Sep 28, 2020 at 11:29:41AM -0400, Mike Snitzer wrote:
This backport applies (with mild offset) to both v5.4.67 and v5.8.11:
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
What is the git id of this patch in Linus's tree?
thanks,
greg k-h
On Mon, Sep 28, 2020 at 07:31:44PM +0200, Greg KH wrote:
On Mon, Sep 28, 2020 at 11:29:41AM -0400, Mike Snitzer wrote:
This backport applies (with mild offset) to both v5.4.67 and v5.8.11:
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
What is the git id of this patch in Linus's tree?
I dug it up: ee1dfad5325f ("dm: fix bio splitting and its bio completion order for regular IO")
On Mon, Sep 28 2020 at 1:52pm -0400, Greg KH gregkh@linuxfoundation.org wrote:
On Mon, Sep 28, 2020 at 07:31:44PM +0200, Greg KH wrote:
On Mon, Sep 28, 2020 at 11:29:41AM -0400, Mike Snitzer wrote:
This backport applies (with mild offset) to both v5.4.67 and v5.8.11:
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
What is the git id of this patch in Linus's tree?
I dug it up: ee1dfad5325f ("dm: fix bio splitting and its bio completion order for regular IO")
I thought this line was adequate in my original email: "From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001"
Maybe it was too subtle? For future knowledge, how would you like to see the git id of Linus's tree referenced?
Thanks, Mike
On Mon, Sep 28, 2020 at 02:03:26PM -0400, Mike Snitzer wrote:
On Mon, Sep 28 2020 at 1:52pm -0400, Greg KH gregkh@linuxfoundation.org wrote:
On Mon, Sep 28, 2020 at 07:31:44PM +0200, Greg KH wrote:
On Mon, Sep 28, 2020 at 11:29:41AM -0400, Mike Snitzer wrote:
This backport applies (with mild offset) to both v5.4.67 and v5.8.11:
From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001
From: Mike Snitzer snitzer@redhat.com Date: Mon, 14 Sep 2020 13:04:19 -0400 Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO
dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split.
Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool).
This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided.
Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com
What is the git id of this patch in Linus's tree?
I dug it up: ee1dfad5325f ("dm: fix bio splitting and its bio completion order for regular IO")
I thought this line was adequate in my original email: "From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001"
Maybe it was too subtle? For future knowledge, how would you like to see the git id of Linus's tree referenced?
Oh, that was subtle, sorry, missed it :)
Better ways can be in that sentence that said what trees to backport it to, right? Explicit is good, especially when having to deal with as many patches as we deal with, right?
thanks,
greg k-h
linux-stable-mirror@lists.linaro.org
-
Greg KH -
gregkh＠linuxfoundation.org
-
Mike Snitzer