* [PATCH] do_generic_file_read(): Fail immediately if killed
@ 2016-08-17 0:00 Bart Van Assche
2016-08-17 10:01 ` Jan Kara
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Bart Van Assche @ 2016-08-17 0:00 UTC (permalink / raw)
To: Andrew Morton
Cc: Mel Gorman, Jan Kara, Hugh Dickins, Oleg Nesterov, linux-mm,
Linux-fsdevel
If a fatal signal has been received, fail immediately instead of
trying to read more data.
See also commit ebded02788b5 ("mm: filemap: avoid unnecessary
calls to lock_page when waiting for IO to complete during a read")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
---
mm/filemap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 2a9e84f6..bd8ab63 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1721,7 +1721,9 @@ find_page:
* wait_on_page_locked is used to avoid unnecessarily
* serialisations and why it's safe.
*/
- wait_on_page_locked_killable(page);
+ error = wait_on_page_locked_killable(page);
+ if (unlikely(error))
+ goto readpage_error;
if (PageUptodate(page))
goto page_ok;
--
2.9.2
--
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] do_generic_file_read(): Fail immediately if killed
2016-08-17 0:00 [PATCH] do_generic_file_read(): Fail immediately if killed Bart Van Assche
@ 2016-08-17 10:01 ` Jan Kara
2016-08-17 16:23 ` Bart Van Assche
2016-08-17 13:48 ` Oleg Nesterov
2016-08-17 17:20 ` Michal Hocko
2 siblings, 1 reply; 5+ messages in thread
From: Jan Kara @ 2016-08-17 10:01 UTC (permalink / raw)
To: Bart Van Assche
Cc: Andrew Morton, Mel Gorman, Jan Kara, Hugh Dickins, Oleg Nesterov,
linux-mm, Linux-fsdevel
On Tue 16-08-16 17:00:43, Bart Van Assche wrote:
> If a fatal signal has been received, fail immediately instead of
> trying to read more data.
>
> See also commit ebded02788b5 ("mm: filemap: avoid unnecessary
> calls to lock_page when waiting for IO to complete during a read")
>
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
BTW: Did you see some real world impact of the change? If yes, it would be
good to describe in the changelog.
Honza
> ---
> mm/filemap.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 2a9e84f6..bd8ab63 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1721,7 +1721,9 @@ find_page:
> * wait_on_page_locked is used to avoid unnecessarily
> * serialisations and why it's safe.
> */
> - wait_on_page_locked_killable(page);
> + error = wait_on_page_locked_killable(page);
> + if (unlikely(error))
> + goto readpage_error;
> if (PageUptodate(page))
> goto page_ok;
>
> --
> 2.9.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] do_generic_file_read(): Fail immediately if killed
2016-08-17 0:00 [PATCH] do_generic_file_read(): Fail immediately if killed Bart Van Assche
2016-08-17 10:01 ` Jan Kara
@ 2016-08-17 13:48 ` Oleg Nesterov
2016-08-17 17:20 ` Michal Hocko
2 siblings, 0 replies; 5+ messages in thread
From: Oleg Nesterov @ 2016-08-17 13:48 UTC (permalink / raw)
To: Bart Van Assche
Cc: Andrew Morton, Mel Gorman, Jan Kara, Hugh Dickins, linux-mm,
Linux-fsdevel
On 08/16, Bart Van Assche wrote:
>
> If a fatal signal has been received, fail immediately instead of
> trying to read more data.
This looks a bit misleading to me.
If wait_on_page_locked_killable() was interrupted then this page is most
likely is not PageUptodate() and in this case do_generic_file_read() will
fail after lock_page_killable().
But as I already said, I belive the change itself is fine,
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1721,7 +1721,9 @@ find_page:
> * wait_on_page_locked is used to avoid unnecessarily
> * serialisations and why it's safe.
> */
> - wait_on_page_locked_killable(page);
> + error = wait_on_page_locked_killable(page);
> + if (unlikely(error))
> + goto readpage_error;
> if (PageUptodate(page))
> goto page_ok;
Acked-by: Oleg Nesterov <oleg@redhat.com>
--
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] do_generic_file_read(): Fail immediately if killed
2016-08-17 10:01 ` Jan Kara
@ 2016-08-17 16:23 ` Bart Van Assche
0 siblings, 0 replies; 5+ messages in thread
From: Bart Van Assche @ 2016-08-17 16:23 UTC (permalink / raw)
To: Jan Kara
Cc: Andrew Morton, Mel Gorman, Hugh Dickins, Oleg Nesterov, linux-mm,
Linux-fsdevel
On 08/17/2016 03:02 AM, Jan Kara wrote:
> On Tue 16-08-16 17:00:43, Bart Van Assche wrote:
>> If a fatal signal has been received, fail immediately instead of
>> trying to read more data.
>>
>> See also commit ebded02788b5 ("mm: filemap: avoid unnecessary
>> calls to lock_page when waiting for IO to complete during a read")
>
> The patch looks good to me. You can add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
>
> BTW: Did you see some real world impact of the change? If yes, it would be
> good to describe in the changelog.
Hello Jan,
Thanks for the review.
This patch has an impact on my tests. However, I do not yet have a full
root-cause analysis for what I observed in my tests. That is why I
hadn't mentioned any further details in the patch description.
While running fio on top of a filesystem (ext4 or xfs), dm-mpath and
the ib_srp driver I noticed that removing and restoring paths triggered
several types of hangs. The call trace of one of these hangs, the one
that made me look at do_generic_file_read(), can be found below. I'm
currently testing a block layer patch to see whether it resolves this
hang.
Bart.
kpartx D ffff8800409d3be8 0 16392 16355 0x00000000
Call Trace:
[<ffffffff8161f577>] schedule+0x37/0x90
[<ffffffff81623bcf>] schedule_timeout+0x27f/0x470
[<ffffffff8161e94f>] io_schedule_timeout+0x9f/0x110
[<ffffffff8161fd16>] bit_wait_io+0x16/0x60
[<ffffffff8161f9a6>] __wait_on_bit+0x56/0x80
[<ffffffff81152e2d>] wait_on_page_bit_killable+0xbd/0xc0
[<ffffffff81152f60>] generic_file_read_iter+0x130/0x770
[<ffffffff812134b0>] blkdev_read_iter+0x30/0x40
[<ffffffff811d267b>] __vfs_read+0xbb/0x130
[<ffffffff811d2a61>] vfs_read+0x91/0x130
[<ffffffff811d3de4>] SyS_read+0x44/0xa0
[<ffffffff81624fa5>] entry_SYSCALL_64_fastpath+0x18/0xa8
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] do_generic_file_read(): Fail immediately if killed
2016-08-17 0:00 [PATCH] do_generic_file_read(): Fail immediately if killed Bart Van Assche
2016-08-17 10:01 ` Jan Kara
2016-08-17 13:48 ` Oleg Nesterov
@ 2016-08-17 17:20 ` Michal Hocko
2 siblings, 0 replies; 5+ messages in thread
From: Michal Hocko @ 2016-08-17 17:20 UTC (permalink / raw)
To: Bart Van Assche
Cc: Andrew Morton, Mel Gorman, Jan Kara, Hugh Dickins, Oleg Nesterov,
linux-mm, Linux-fsdevel
On Tue 16-08-16 17:00:43, Bart Van Assche wrote:
> If a fatal signal has been received, fail immediately instead of
> trying to read more data.
>
> See also commit ebded02788b5 ("mm: filemap: avoid unnecessary
> calls to lock_page when waiting for IO to complete during a read")
>
> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
If not anything else it makes code more readable because the real error
is hidden in page_not_up_to_date: currently...
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/filemap.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 2a9e84f6..bd8ab63 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1721,7 +1721,9 @@ find_page:
> * wait_on_page_locked is used to avoid unnecessarily
> * serialisations and why it's safe.
> */
> - wait_on_page_locked_killable(page);
> + error = wait_on_page_locked_killable(page);
> + if (unlikely(error))
> + goto readpage_error;
> if (PageUptodate(page))
> goto page_ok;
>
> --
> 2.9.2
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
Michal Hocko
SUSE Labs
--
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-08-17 17:20 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2016-08-17 0:00 [PATCH] do_generic_file_read(): Fail immediately if killed Bart Van Assche
2016-08-17 10:01 ` Jan Kara
2016-08-17 16:23 ` Bart Van Assche
2016-08-17 13:48 ` Oleg Nesterov
2016-08-17 17:20 ` Michal Hocko
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