The patch titled
Subject: zram: fix return value on writeback_store
has been added to the -mm tree. Its filename is
zram-fix-return-value-on-writeback_store.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/zram-fix-return-value-on-writeback_store.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/zram-fix-return-value-on-writeback_store.patch
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The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zram: fix return value on writeback_store
writeback_store's return value is overwritten by submit_bio_wait's return
value. Thus, writeback_store will return zero since there was no IO
error. In the end, write syscall from userspace will see the zero as
return value, which could make the process stall to keep trying the write
until it will succeed.
Link: https://lkml.kernel.org/r/20210312173949.2197662-1-minchan@xxxxxxxxxx
Fixes: 3b82a051c101("drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store")
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Cc: John Dias <joaodias@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/block/zram/zram_drv.c~zram-fix-return-value-on-writeback_store
+++ a/drivers/block/zram/zram_drv.c
@@ -627,7 +627,7 @@ static ssize_t writeback_store(struct de
struct bio_vec bio_vec;
struct page *page;
ssize_t ret = len;
- int mode;
+ int mode, err;
unsigned long blk_idx = 0;
if (sysfs_streq(buf, "idle"))
@@ -728,12 +728,17 @@ static ssize_t writeback_store(struct de
* XXX: A single page IO would be inefficient for write
* but it would be not bad as starter.
*/
- ret = submit_bio_wait(&bio);
- if (ret) {
+ err = submit_bio_wait(&bio);
+ if (err) {
zram_slot_lock(zram, index);
zram_clear_flag(zram, index, ZRAM_UNDER_WB);
zram_clear_flag(zram, index, ZRAM_IDLE);
zram_slot_unlock(zram, index);
+ /*
+ * Return last IO error unless every IO were
+ * not suceeded.
+ */
+ ret = err;
continue;
}
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
zram-fix-return-value-on-writeback_store.patch
zram-fix-broken-page-writeback.patch
mm-remove-lru_add_drain_all-in-alloc_contig_range.patch
mm-page_alloc-dump-migrate-failed-pages.patch
mm-vmstat-add-cma-statistics.patch
mm-cma-support-sysfs.patch
