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.
Cc: stable(a)vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe(a)kernel.dk>
---
drivers/block/brd.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 15a148d5aad9..1ddada0cdaca 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -80,26 +80,20 @@ 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;
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 (radix_tree_preload(gfp)) {
__free_page(page);
return -ENOMEM;
}
@@ -167,19 +161,20 @@ 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 +249,26 @@ 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 +297,12 @@ 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;
}
--
2.39.1
During page migration, the copy_highpage function is used to copy the
page data to the target page. If the source page is a userspace page
with MTE tags, the KASAN tag of the target page must have the match-all
tag in order to avoid tag check faults during subsequent accesses to the
page by the kernel. However, the target page may have been allocated in
a number of ways, some of which will use the KASAN allocator and will
therefore end up setting the KASAN tag to a non-match-all tag. Therefore,
update the target page's KASAN tag to match the source page.
We ended up unintentionally fixing this issue as a result of a bad
merge conflict resolution between commit e059853d14ca ("arm64: mte:
Fix/clarify the PG_mte_tagged semantics") and commit 20794545c146 ("arm64:
kasan: Revert "arm64: mte: reset the page tag in page->flags""), which
preserved a tag reset for PG_mte_tagged pages which was considered to be
unnecessary at the time. Because SW tags KASAN uses separate tag storage,
update the code to only reset the tags when HW tags KASAN is enabled.
Signed-off-by: Peter Collingbourne <pcc(a)google.com>
Link: https://linux-review.googlesource.com/id/If303d8a709438d3ff5af5fd8570650583…
Reported-by: "Kuan-Ying Lee (李冠穎)" <Kuan-Ying.Lee(a)mediatek.com>
Cc: <stable(a)vger.kernel.org> # 6.1
---
For the stable branch, e059853d14ca needs to be cherry-picked and the following
merge conflict resolution is needed:
- page_kasan_tag_reset(to);
+ if (kasan_hw_tags_enabled())
+ page_kasan_tag_reset(to);
- /* It's a new page, shouldn't have been tagged yet */
- WARN_ON_ONCE(!try_page_mte_tagging(to));
arch/arm64/mm/copypage.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
index 8dd5a8fe64b4..4aadcfb01754 100644
--- a/arch/arm64/mm/copypage.c
+++ b/arch/arm64/mm/copypage.c
@@ -22,7 +22,8 @@ void copy_highpage(struct page *to, struct page *from)
copy_page(kto, kfrom);
if (system_supports_mte() && page_mte_tagged(from)) {
- page_kasan_tag_reset(to);
+ if (kasan_hw_tags_enabled())
+ page_kasan_tag_reset(to);
/* It's a new page, shouldn't have been tagged yet */
WARN_ON_ONCE(!try_page_mte_tagging(to));
mte_copy_page_tags(kto, kfrom);
--
2.39.1.581.gbfd45094c4-goog