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* [PATCH] mm: migrate: initialize err in do_migrate_pages
@ 2021-01-05 14:14 Jan Stancek
  2021-01-05 14:24 ` Michal Hocko
  2021-01-05 17:14   ` Yang Shi
  0 siblings, 2 replies; 4+ messages in thread
From: Jan Stancek @ 2021-01-05 14:14 UTC (permalink / raw)
  To: linux-mm, linux-kernel
  Cc: ziy, shy828301, jack, willy, mgorman, mhocko, songliubraving,
	akpm, jstancek

After commit 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")',
do_migrate_pages can return uninitialized variable 'err' (which is
propagated to user-space as error) when 'from' and 'to' nodesets
are identical. This can be reproduced with LTP migrate_pages01,
which calls migrate_pages() with same set for both old/new_nodes.

Add 'err' initialization back.

Fixes: 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 mm/mempolicy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8cf96bd21341..2c3a86502053 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1111,7 +1111,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
 		     const nodemask_t *to, int flags)
 {
 	int busy = 0;
-	int err;
+	int err = 0;
 	nodemask_t tmp;
 
 	migrate_prep();
-- 
2.18.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: migrate: initialize err in do_migrate_pages
  2021-01-05 14:14 [PATCH] mm: migrate: initialize err in do_migrate_pages Jan Stancek
@ 2021-01-05 14:24 ` Michal Hocko
  2021-01-05 17:14   ` Yang Shi
  1 sibling, 0 replies; 4+ messages in thread
From: Michal Hocko @ 2021-01-05 14:24 UTC (permalink / raw)
  To: Jan Stancek
  Cc: linux-mm, linux-kernel, ziy, shy828301, jack, willy, mgorman,
	songliubraving, akpm

On Tue 05-01-21 15:14:20, Jan Stancek wrote:
> After commit 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")',
> do_migrate_pages can return uninitialized variable 'err' (which is
> propagated to user-space as error) when 'from' and 'to' nodesets
> are identical. This can be reproduced with LTP migrate_pages01,
> which calls migrate_pages() with same set for both old/new_nodes.
> 
> Add 'err' initialization back.
> 
> Fixes: 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Song Liu <songliubraving@fb.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!

> ---
>  mm/mempolicy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 8cf96bd21341..2c3a86502053 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1111,7 +1111,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
>  		     const nodemask_t *to, int flags)
>  {
>  	int busy = 0;
> -	int err;
> +	int err = 0;
>  	nodemask_t tmp;
>  
>  	migrate_prep();
> -- 
> 2.18.1
> 

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: migrate: initialize err in do_migrate_pages
  2021-01-05 14:14 [PATCH] mm: migrate: initialize err in do_migrate_pages Jan Stancek
@ 2021-01-05 17:14   ` Yang Shi
  2021-01-05 17:14   ` Yang Shi
  1 sibling, 0 replies; 4+ messages in thread
From: Yang Shi @ 2021-01-05 17:14 UTC (permalink / raw)
  To: Jan Stancek
  Cc: Linux MM, Linux Kernel Mailing List, Zi Yan, Jan Kara,
	Matthew Wilcox, Mel Gorman, Michal Hocko, Song Liu,
	Andrew Morton

On Tue, Jan 5, 2021 at 6:14 AM Jan Stancek <jstancek@redhat.com> wrote:
>
> After commit 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")',
> do_migrate_pages can return uninitialized variable 'err' (which is
> propagated to user-space as error) when 'from' and 'to' nodesets
> are identical. This can be reproduced with LTP migrate_pages01,
> which calls migrate_pages() with same set for both old/new_nodes.
>
> Add 'err' initialization back.

Thanks for catching this. Acked-by: Yang Shi <shy828301@gmail.com>

>
> Fixes: 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Song Liu <songliubraving@fb.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  mm/mempolicy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 8cf96bd21341..2c3a86502053 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1111,7 +1111,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
>                      const nodemask_t *to, int flags)
>  {
>         int busy = 0;
> -       int err;
> +       int err = 0;
>         nodemask_t tmp;
>
>         migrate_prep();
> --
> 2.18.1
>

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: migrate: initialize err in do_migrate_pages
@ 2021-01-05 17:14   ` Yang Shi
  0 siblings, 0 replies; 4+ messages in thread
From: Yang Shi @ 2021-01-05 17:14 UTC (permalink / raw)
  To: Jan Stancek
  Cc: Linux MM, Linux Kernel Mailing List, Zi Yan, Jan Kara,
	Matthew Wilcox, Mel Gorman, Michal Hocko, Song Liu,
	Andrew Morton

On Tue, Jan 5, 2021 at 6:14 AM Jan Stancek <jstancek@redhat.com> wrote:
>
> After commit 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")',
> do_migrate_pages can return uninitialized variable 'err' (which is
> propagated to user-space as error) when 'from' and 'to' nodesets
> are identical. This can be reproduced with LTP migrate_pages01,
> which calls migrate_pages() with same set for both old/new_nodes.
>
> Add 'err' initialization back.

Thanks for catching this. Acked-by: Yang Shi <shy828301@gmail.com>

>
> Fixes: 236c32eb1096 ("mm: migrate: clean up migrate_prep{_local}")
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Song Liu <songliubraving@fb.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  mm/mempolicy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 8cf96bd21341..2c3a86502053 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1111,7 +1111,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
>                      const nodemask_t *to, int flags)
>  {
>         int busy = 0;
> -       int err;
> +       int err = 0;
>         nodemask_t tmp;
>
>         migrate_prep();
> --
> 2.18.1
>


^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-01-05 17:15 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-05 14:14 [PATCH] mm: migrate: initialize err in do_migrate_pages Jan Stancek
2021-01-05 14:24 ` Michal Hocko
2021-01-05 17:14 ` Yang Shi
2021-01-05 17:14   ` Yang Shi

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