* + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch
@ 2022-05-12 20:45 Andrew Morton
2022-05-12 21:28 ` Minchan Kim
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2022-05-12 20:45 UTC (permalink / raw)
To: mm-commits, paulmck, jhubbard, david, minchan, akpm
The patch titled
Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
has been added to the -mm mm-unstable branch. Its filename is
mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Minchan Kim <minchan@kernel.org>
Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
* clarification why we need READ_ONCE - Paul
* Add a comment about READ_ONCE - John
Link: https://lkml.kernel.org/r/20220512204143.3961150-1-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/include/linux/mm.h~mm-fix-is_pinnable_page-against-on-cma-page-v5
+++ a/include/linux/mm.h
@@ -1627,13 +1627,14 @@ static inline bool is_pinnable_page(stru
{
#ifdef CONFIG_CMA
/*
- * use volatile to use local variable mt instead of
- * refetching mt value.
+ * Defend against future compiler LTO features, or code refactoring
+ * that inlines the above function, by forcing a single read. Because,
+ * this routine races with set_pageblock_migratetype(), and we want to
+ * avoid reading zero, when actually one or the other flags was set.
*/
- int __mt = get_pageblock_migratetype(page);
int mt = __READ_ONCE(__mt);
- if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
+ if (mt & (MIGRATE_CMA | MIGRATE_ISOLATE))
return false;
#endif
_
Patches currently in -mm which might be from minchan@kernel.org are
mm-fix-is_pinnable_page-against-on-cma-page.patch
mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
mm-dont-be-stuck-to-rmap-lock-on-reclaim-path.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch
2022-05-12 20:45 + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch Andrew Morton
@ 2022-05-12 21:28 ` Minchan Kim
2022-05-12 21:34 ` Minchan Kim
0 siblings, 1 reply; 3+ messages in thread
From: Minchan Kim @ 2022-05-12 21:28 UTC (permalink / raw)
To: Andrew Morton; +Cc: mm-commits, paulmck, jhubbard, david
On Thu, May 12, 2022 at 01:45:05PM -0700, Andrew Morton wrote:
>
> The patch titled
> Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
> has been added to the -mm mm-unstable branch. Its filename is
> mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
>
> This patch will shortly appear at
> https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
>
> This patch will later appear in the mm-unstable branch at
> git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
>
> Before you just go and hit "reply", please:
> a) Consider who else should be cc'ed
> b) Prefer to cc a suitable mailing list as well
> c) Ideally: find the original patch on the mailing list and do a
> reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
> The -mm tree is included into linux-next via the mm-everything
> branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> and is updated there every 2-3 working days
>
> ------------------------------------------------------
> From: Minchan Kim <minchan@kernel.org>
> Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
>
> * clarification why we need READ_ONCE - Paul
> * Add a comment about READ_ONCE - John
>
> Link: https://lkml.kernel.org/r/20220512204143.3961150-1-minchan@kernel.org
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> Cc: "Paul E . McKenney" <paulmck@kernel.org>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: David Hildenbrand <david@redhat.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> include/linux/mm.h | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> --- a/include/linux/mm.h~mm-fix-is_pinnable_page-against-on-cma-page-v5
> +++ a/include/linux/mm.h
> @@ -1627,13 +1627,14 @@ static inline bool is_pinnable_page(stru
> {
> #ifdef CONFIG_CMA
> /*
> - * use volatile to use local variable mt instead of
> - * refetching mt value.
> + * Defend against future compiler LTO features, or code refactoring
> + * that inlines the above function, by forcing a single read. Because,
> + * this routine races with set_pageblock_migratetype(), and we want to
> + * avoid reading zero, when actually one or the other flags was set.
> */
> - int __mt = get_pageblock_migratetype(page);
It makes build failure.
Could you pick this up instead?
https://lore.kernel.org/all/Yn10GkInyZNtqASa@google.com/
Sorry for confusing.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch
2022-05-12 21:28 ` Minchan Kim
@ 2022-05-12 21:34 ` Minchan Kim
0 siblings, 0 replies; 3+ messages in thread
From: Minchan Kim @ 2022-05-12 21:34 UTC (permalink / raw)
To: Andrew Morton; +Cc: mm-commits, paulmck, jhubbard, david
On Thu, May 12, 2022 at 02:28:33PM -0700, Minchan Kim wrote:
> On Thu, May 12, 2022 at 01:45:05PM -0700, Andrew Morton wrote:
> >
> > The patch titled
> > Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
> > has been added to the -mm mm-unstable branch. Its filename is
> > mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
> >
> > This patch will shortly appear at
> > https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-is_pinnable_page-against-on-cma-page-v5.patch
> >
> > This patch will later appear in the mm-unstable branch at
> > git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> >
> > Before you just go and hit "reply", please:
> > a) Consider who else should be cc'ed
> > b) Prefer to cc a suitable mailing list as well
> > c) Ideally: find the original patch on the mailing list and do a
> > reply-to-all to that, adding suitable additional cc's
> >
> > *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> >
> > The -mm tree is included into linux-next via the mm-everything
> > branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> > and is updated there every 2-3 working days
> >
> > ------------------------------------------------------
> > From: Minchan Kim <minchan@kernel.org>
> > Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5
> >
> > * clarification why we need READ_ONCE - Paul
> > * Add a comment about READ_ONCE - John
> >
> > Link: https://lkml.kernel.org/r/20220512204143.3961150-1-minchan@kernel.org
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > Cc: "Paul E . McKenney" <paulmck@kernel.org>
> > Cc: John Hubbard <jhubbard@nvidia.com>
> > Cc: David Hildenbrand <david@redhat.com>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> > ---
> >
> > include/linux/mm.h | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > --- a/include/linux/mm.h~mm-fix-is_pinnable_page-against-on-cma-page-v5
> > +++ a/include/linux/mm.h
> > @@ -1627,13 +1627,14 @@ static inline bool is_pinnable_page(stru
> > {
> > #ifdef CONFIG_CMA
> > /*
> > - * use volatile to use local variable mt instead of
> > - * refetching mt value.
> > + * Defend against future compiler LTO features, or code refactoring
> > + * that inlines the above function, by forcing a single read. Because,
> > + * this routine races with set_pageblock_migratetype(), and we want to
> > + * avoid reading zero, when actually one or the other flags was set.
> > */
> > - int __mt = get_pageblock_migratetype(page);
>
> It makes build failure.
>
> Could you pick this up instead?
>
> https://lore.kernel.org/all/Yn10GkInyZNtqASa@google.com/
I really don't understand why it works or don't sometimes
At least, it works
https://lore.kernel.org/lkml/Yn10GkInyZNtqASa@google.com/
>
> Sorry for confusing.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-05-12 20:45 + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch Andrew Morton
2022-05-12 21:28 ` Minchan Kim
2022-05-12 21:34 ` Minchan Kim
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