This is a note to let you know that I've just added the patch titled
zram: fix return value on writeback_store
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-fix-return-value-on-writeback_store.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 57e0076e6575a7b7cef620a0bd2ee2549ef77818 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Fri, 12 Mar 2021 21:08:38 -0800
Subject: zram: fix return value on writeback_store
From: Minchan Kim <minchan@xxxxxxxxxx>
commit 57e0076e6575a7b7cef620a0bd2ee2549ef77818 upstream.
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>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -633,7 +633,7 @@ 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"))
@@ -725,12 +725,17 @@ 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 stable-queue which might be from minchan@xxxxxxxxxx are
queue-5.10/zram-fix-return-value-on-writeback_store.patch
queue-5.10/mm-madvise-replace-ptrace-attach-requirement-for-process_madvise.patch
queue-5.10/mm-userfaultfd-fix-memory-corruption-due-to-writeprotect.patch
