The patch below does not apply to the 5.15-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@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6ded703c56c21bfb259725d4f1831a5feb563e9b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '1678125031200144@xxxxxxxxx' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 6ded703c56c2 ("brd: check for REQ_NOWAIT and set correct page allocation mask") db0ccc44a20b ("brd: return 0/-error from brd_insert_page()") ba91fd01aad2 ("block/brd: Use the enum req_op type") 3e08773c3841 ("block: switch polling to be bio based") 6ce913fe3eee ("block: rename REQ_HIPRI to REQ_POLLED") d729cf9acb93 ("io_uring: don't sleep when polling for I/O") ef99b2d37666 ("block: replace the spin argument to blk_iopoll with a flags argument") 28a1ae6b9dab ("blk-mq: remove blk_qc_t_valid") efbabbe121f9 ("blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal") c6699d6fe0ff ("blk-mq: factor out a "classic" poll helper") f70299f0d58e ("blk-mq: factor out a blk_qc_to_hctx helper") 71fc3f5e2c00 ("block: don't try to poll multi-bio I/Os in __blkdev_direct_IO") 0f38d7664615 ("blk-mq: cleanup blk_mq_submit_bio") 47c122e35d7e ("block: pre-allocate requests if plug is started and is a batch") 24b83deb29b7 ("block: move struct request to blk-mq.h") badf7f643787 ("block: move a few merge helpers out of <linux/blkdev.h>") 2e9bc3465ac5 ("block: move elevator.h to block/") 9778ac77c202 ("block: remove the struct blk_queue_ctx forward declaration") 90138237a562 ("block: remove the unused blk_queue_state enum") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6ded703c56c21bfb259725d4f1831a5feb563e9b Mon Sep 17 00:00:00 2001 From: Jens Axboe <axboe@xxxxxxxxx> Date: Thu, 16 Feb 2023 08:01:08 -0700 Subject: [PATCH] brd: check for REQ_NOWAIT and set correct page allocation mask If REQ_NOWAIT is set, then do a non-blocking allocation if the operation is a write and we need to insert a new page. Currently REQ_NOWAIT cannot be set as the queue isn't marked as supporting nowait, this change is in preparation for allowing that. radix_tree_preload() warns on attempting to call it with an allocation mask that doesn't allow blocking. While that warning could arguably be removed, we need to handle radix insertion failures anyway as they are more likely if we cannot block to get memory. Remove legacy BUG_ON()'s and turn them into proper errors instead, one for the allocation failure and one for finding a page that doesn't match the correct index. Cc: stable@xxxxxxxxxxxxxxx # 5.10+ Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 15a148d5aad9..00f3c5b51a01 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -80,26 +80,21 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) /* * Insert a new page for a given sector, if one does not already exist. */ -static int brd_insert_page(struct brd_device *brd, sector_t sector) +static int brd_insert_page(struct brd_device *brd, sector_t sector, gfp_t gfp) { pgoff_t idx; struct page *page; - gfp_t gfp_flags; + int ret = 0; page = brd_lookup_page(brd, sector); if (page) return 0; - /* - * Must use NOIO because we don't want to recurse back into the - * block or filesystem layers from page reclaim. - */ - gfp_flags = GFP_NOIO | __GFP_ZERO | __GFP_HIGHMEM; - page = alloc_page(gfp_flags); + page = alloc_page(gfp | __GFP_ZERO | __GFP_HIGHMEM); if (!page) return -ENOMEM; - if (radix_tree_preload(GFP_NOIO)) { + if (gfpflags_allow_blocking(gfp) && radix_tree_preload(gfp)) { __free_page(page); return -ENOMEM; } @@ -110,15 +105,17 @@ static int brd_insert_page(struct brd_device *brd, sector_t sector) if (radix_tree_insert(&brd->brd_pages, idx, page)) { __free_page(page); page = radix_tree_lookup(&brd->brd_pages, idx); - BUG_ON(!page); - BUG_ON(page->index != idx); + if (!page) + ret = -ENOMEM; + else if (page->index != idx) + ret = -EIO; } else { brd->brd_nr_pages++; } spin_unlock(&brd->brd_lock); radix_tree_preload_end(); - return 0; + return ret; } /* @@ -167,19 +164,20 @@ static void brd_free_pages(struct brd_device *brd) /* * copy_to_brd_setup must be called before copy_to_brd. It may sleep. */ -static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) +static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n, + gfp_t gfp) { unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; size_t copy; int ret; copy = min_t(size_t, n, PAGE_SIZE - offset); - ret = brd_insert_page(brd, sector); + ret = brd_insert_page(brd, sector, gfp); if (ret) return ret; if (copy < n) { sector += copy >> SECTOR_SHIFT; - ret = brd_insert_page(brd, sector); + ret = brd_insert_page(brd, sector, gfp); } return ret; } @@ -254,20 +252,26 @@ static void copy_from_brd(void *dst, struct brd_device *brd, * Process a single bvec of a bio. */ static int brd_do_bvec(struct brd_device *brd, struct page *page, - unsigned int len, unsigned int off, enum req_op op, + unsigned int len, unsigned int off, blk_opf_t opf, sector_t sector) { void *mem; int err = 0; - if (op_is_write(op)) { - err = copy_to_brd_setup(brd, sector, len); + if (op_is_write(opf)) { + /* + * Must use NOIO because we don't want to recurse back into the + * block or filesystem layers from page reclaim. + */ + gfp_t gfp = opf & REQ_NOWAIT ? GFP_NOWAIT : GFP_NOIO; + + err = copy_to_brd_setup(brd, sector, len, gfp); if (err) goto out; } mem = kmap_atomic(page); - if (!op_is_write(op)) { + if (!op_is_write(opf)) { copy_from_brd(mem + off, brd, sector, len); flush_dcache_page(page); } else { @@ -296,8 +300,12 @@ static void brd_submit_bio(struct bio *bio) (len & (SECTOR_SIZE - 1))); err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset, - bio_op(bio), sector); + bio->bi_opf, sector); if (err) { + if (err == -ENOMEM && bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } bio_io_error(bio); return; }
