mm/vmstat.c | 1 - 1 file changed, 1 deletion(-)
Hongyu noticed that the nr_unaccepted counter kept growing even in the
absence of unaccepted memory on the machine.
This happens due to a commit that removed NR_BOUNCE: it removed the
counter from the enum zone_stat_item, but left it in the vmstat_text
array.
As a result, all counters below nr_bounce in /proc/vmstat are
shifted by one line, causing the numa_hit counter to be labeled as
nr_unaccepted.
To fix this issue, remove nr_bounce from the vmstat_text array.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
Cc: stable@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Jens Axboe <axboe@kernel.dk>
---
mm/vmstat.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4c268ce39ff2..ae9882063d89 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1201,7 +1201,6 @@ const char * const vmstat_text[] = {
"nr_zone_unevictable",
"nr_zone_write_pending",
"nr_mlock",
- "nr_bounce",
#if IS_ENABLED(CONFIG_ZSMALLOC)
"nr_zspages",
#endif
--
2.47.2On Thu, May 29, 2025 at 01:38:32PM +0300, Kirill A. Shutemov wrote:
> Hongyu noticed that the nr_unaccepted counter kept growing even in the
> absence of unaccepted memory on the machine.
>
> This happens due to a commit that removed NR_BOUNCE: it removed the
> counter from the enum zone_stat_item, but left it in the vmstat_text
> array.
>
> As a result, all counters below nr_bounce in /proc/vmstat are
> shifted by one line, causing the numa_hit counter to be labeled as
> nr_unaccepted.
>
> To fix this issue, remove nr_bounce from the vmstat_text array.
Ooops, yes:
Reviewed-by: Christoph Hellwig <hch@lst.de>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4c268ce39ff2..ae9882063d89 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1201,7 +1201,6 @@ const char * const vmstat_text[] = {
> "nr_zone_unevictable",
> "nr_zone_write_pending",
> "nr_mlock",
> - "nr_bounce",
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> "nr_zspages",
> #endif
It would be really useful if such pretty printing arrays used
named initializers, as that would make it obvious that an entry
needs removal.
On Thu, May 29, 2025 at 01:38:32PM +0300, Kirill A. Shutemov wrote:
> Hongyu noticed that the nr_unaccepted counter kept growing even in the
> absence of unaccepted memory on the machine.
>
> This happens due to a commit that removed NR_BOUNCE: it removed the
> counter from the enum zone_stat_item, but left it in the vmstat_text
> array.
>
> As a result, all counters below nr_bounce in /proc/vmstat are
> shifted by one line, causing the numa_hit counter to be labeled as
> nr_unaccepted.
>
> To fix this issue, remove nr_bounce from the vmstat_text array.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> Cc: stable@vger.kernel.org
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Can we put BUILD_BUG_ON() to avoid this situation in the future?
On Thu 29-05-25 13:38:32, Kirill A. Shutemov wrote:
> Hongyu noticed that the nr_unaccepted counter kept growing even in the
> absence of unaccepted memory on the machine.
>
> This happens due to a commit that removed NR_BOUNCE: it removed the
> counter from the enum zone_stat_item, but left it in the vmstat_text
> array.
>
> As a result, all counters below nr_bounce in /proc/vmstat are
> shifted by one line, causing the numa_hit counter to be labeled as
> nr_unaccepted.
>
> To fix this issue, remove nr_bounce from the vmstat_text array.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> Cc: stable@vger.kernel.org
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
Acked-by: Michal Hocko <mhocko@suse.com>
Unfortunatelly a common mistake to make. I have seen you have a followup
fix with a stricter build time check. Will have a look.
Thanks!
> ---
> mm/vmstat.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4c268ce39ff2..ae9882063d89 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1201,7 +1201,6 @@ const char * const vmstat_text[] = {
> "nr_zone_unevictable",
> "nr_zone_write_pending",
> "nr_mlock",
> - "nr_bounce",
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> "nr_zspages",
> #endif
> --
> 2.47.2
--
Michal Hocko
SUSE Labs
On 5/29/25 12:38, Kirill A. Shutemov wrote:
> Hongyu noticed that the nr_unaccepted counter kept growing even in the
> absence of unaccepted memory on the machine.
>
> This happens due to a commit that removed NR_BOUNCE: it removed the
> counter from the enum zone_stat_item, but left it in the vmstat_text
> array.
>
> As a result, all counters below nr_bounce in /proc/vmstat are
> shifted by one line, causing the numa_hit counter to be labeled as
> nr_unaccepted.
>
> To fix this issue, remove nr_bounce from the vmstat_text array.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> Cc: stable@vger.kernel.org
Not necessary, as the fixes commit is from this merge window?
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/vmstat.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4c268ce39ff2..ae9882063d89 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1201,7 +1201,6 @@ const char * const vmstat_text[] = {
> "nr_zone_unevictable",
> "nr_zone_write_pending",
> "nr_mlock",
> - "nr_bounce",
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> "nr_zspages",
> #endif
Hi Kirill,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Kirill-A-Shutemov/mm-Fix-vmstat-after-removing-NR_BOUNCE/20250529-184044
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20250529103832.2937460-1-kirill.shutemov%40linux.intel.com
patch subject: [PATCH] mm: Fix vmstat after removing NR_BOUNCE
config: m68k-allnoconfig (https://download.01.org/0day-ci/archive/20250529/202505291930.NDyeQ06g-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250529/202505291930.NDyeQ06g-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505291930.NDyeQ06g-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from <command-line>:
mm/vmstat.c: In function 'vmstat_start':
>> include/linux/compiler_types.h:563:45: error: call to '__compiletime_assert_318' declared with attribute error: BUILD_BUG_ON failed: ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS
563 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^
include/linux/compiler_types.h:544:25: note: in definition of macro '__compiletime_assert'
544 | prefix ## suffix(); \
| ^~~~~~
include/linux/compiler_types.h:563:9: note: in expansion of macro '_compiletime_assert'
563 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
| ^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
| ^~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
| ^~~~~~~~~~~~~~~~
mm/vmstat.c:1872:9: note: in expansion of macro 'BUILD_BUG_ON'
1872 | BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
| ^~~~~~~~~~~~
vim +/__compiletime_assert_318 +563 include/linux/compiler_types.h
eb5c2d4b45e3d2 Will Deacon 2020-07-21 549
eb5c2d4b45e3d2 Will Deacon 2020-07-21 550 #define _compiletime_assert(condition, msg, prefix, suffix) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21 551 __compiletime_assert(condition, msg, prefix, suffix)
eb5c2d4b45e3d2 Will Deacon 2020-07-21 552
eb5c2d4b45e3d2 Will Deacon 2020-07-21 553 /**
eb5c2d4b45e3d2 Will Deacon 2020-07-21 554 * compiletime_assert - break build and emit msg if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21 555 * @condition: a compile-time constant condition to check
eb5c2d4b45e3d2 Will Deacon 2020-07-21 556 * @msg: a message to emit if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21 557 *
eb5c2d4b45e3d2 Will Deacon 2020-07-21 558 * In tradition of POSIX assert, this macro will break the build if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21 559 * supplied condition is *false*, emitting the supplied error message if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21 560 * compiler has support to do so.
eb5c2d4b45e3d2 Will Deacon 2020-07-21 561 */
eb5c2d4b45e3d2 Will Deacon 2020-07-21 562 #define compiletime_assert(condition, msg) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21 @563 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
eb5c2d4b45e3d2 Will Deacon 2020-07-21 564
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Thu, May 29, 2025 at 07:59:40PM +0800, kernel test robot wrote: > Hi Kirill, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on akpm-mm/mm-everything] > > url: https://github.com/intel-lab-lkp/linux/commits/Kirill-A-Shutemov/mm-Fix-vmstat-after-removing-NR_BOUNCE/20250529-184044 > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything Wrong base. Use Linus' tree instead. -- Kiryl Shutsemau / Kirill A. Shutemov
On 5/29/25 4:38 AM, Kirill A. Shutemov wrote: > Hongyu noticed that the nr_unaccepted counter kept growing even in the > absence of unaccepted memory on the machine. > > This happens due to a commit that removed NR_BOUNCE: it removed the > counter from the enum zone_stat_item, but left it in the vmstat_text > array. > > As a result, all counters below nr_bounce in /proc/vmstat are > shifted by one line, causing the numa_hit counter to be labeled as > nr_unaccepted. > > To fix this issue, remove nr_bounce from the vmstat_text array. Reviewed-by: Jens Axboe <axboe@kernel.dk> > Cc: stable@vger.kernel.org No need for a stable tag, the patch went into the 6.16 merge window. -- Jens Axboe
On 5/29/25 12:38, Kirill A. Shutemov wrote:
> Hongyu noticed that the nr_unaccepted counter kept growing even in the
> absence of unaccepted memory on the machine.
>
> This happens due to a commit that removed NR_BOUNCE: it removed the
> counter from the enum zone_stat_item, but left it in the vmstat_text
> array.
>
> As a result, all counters below nr_bounce in /proc/vmstat are
> shifted by one line, causing the numa_hit counter to be labeled as
> nr_unaccepted.
>
> To fix this issue, remove nr_bounce from the vmstat_text array.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> Cc: stable@vger.kernel.org
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
Is there a way to add a BUILD_BUG_ON to catch a future case like this one?
> ---
> mm/vmstat.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4c268ce39ff2..ae9882063d89 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1201,7 +1201,6 @@ const char * const vmstat_text[] = {
> "nr_zone_unevictable",
> "nr_zone_write_pending",
> "nr_mlock",
> - "nr_bounce",
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> "nr_zspages",
> #endif
On Thu, May 29, 2025 at 12:40:21PM +0200, Vlastimil Babka wrote:
> On 5/29/25 12:38, Kirill A. Shutemov wrote:
> > Hongyu noticed that the nr_unaccepted counter kept growing even in the
> > absence of unaccepted memory on the machine.
> >
> > This happens due to a commit that removed NR_BOUNCE: it removed the
> > counter from the enum zone_stat_item, but left it in the vmstat_text
> > array.
> >
> > As a result, all counters below nr_bounce in /proc/vmstat are
> > shifted by one line, causing the numa_hit counter to be labeled as
> > nr_unaccepted.
> >
> > To fix this issue, remove nr_bounce from the vmstat_text array.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> > Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> > Cc: stable@vger.kernel.org
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Hannes Reinecke <hare@suse.de>
> > Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> > Cc: Jens Axboe <axboe@kernel.dk>
>
> Is there a way to add a BUILD_BUG_ON to catch a future case like this one?
There's
BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
in vmstat_start().
Making it strict != seems to do the trick for my config. But it requires
wider testing.
I can prepare a patch for that.
--
Kiryl Shutsemau / Kirill A. Shutemov
On Thu, May 29, 2025 at 01:47:10PM +0300, Kirill A. Shutemov wrote:
> On Thu, May 29, 2025 at 12:40:21PM +0200, Vlastimil Babka wrote:
> > On 5/29/25 12:38, Kirill A. Shutemov wrote:
> > > Hongyu noticed that the nr_unaccepted counter kept growing even in the
> > > absence of unaccepted memory on the machine.
> > >
> > > This happens due to a commit that removed NR_BOUNCE: it removed the
> > > counter from the enum zone_stat_item, but left it in the vmstat_text
> > > array.
> > >
> > > As a result, all counters below nr_bounce in /proc/vmstat are
> > > shifted by one line, causing the numa_hit counter to be labeled as
> > > nr_unaccepted.
> > >
> > > To fix this issue, remove nr_bounce from the vmstat_text array.
> > >
> > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > > Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> > > Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> > > Cc: stable@vger.kernel.org
> > > Cc: Christoph Hellwig <hch@lst.de>
> > > Cc: Hannes Reinecke <hare@suse.de>
> > > Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> > > Cc: Jens Axboe <axboe@kernel.dk>
> >
> > Is there a way to add a BUILD_BUG_ON to catch a future case like this one?
>
> There's
>
> BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
>
> in vmstat_start().
>
> Making it strict != seems to do the trick for my config. But it requires
> wider testing.
>
> I can prepare a patch for that.
There was a strict check before 9d7ea9a297e6 ("mm/vmstat: add helpers to
get vmstat item names for each enum type"). Not sure if changing != to <
was intentional.
Konstantin?
--
Kiryl Shutsemau / Kirill A. Shutemov
On Thu, 29 May 2025 at 12:51, Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> On Thu, May 29, 2025 at 01:47:10PM +0300, Kirill A. Shutemov wrote:
> > On Thu, May 29, 2025 at 12:40:21PM +0200, Vlastimil Babka wrote:
> > > On 5/29/25 12:38, Kirill A. Shutemov wrote:
> > > > Hongyu noticed that the nr_unaccepted counter kept growing even in the
> > > > absence of unaccepted memory on the machine.
> > > >
> > > > This happens due to a commit that removed NR_BOUNCE: it removed the
> > > > counter from the enum zone_stat_item, but left it in the vmstat_text
> > > > array.
> > > >
> > > > As a result, all counters below nr_bounce in /proc/vmstat are
> > > > shifted by one line, causing the numa_hit counter to be labeled as
> > > > nr_unaccepted.
> > > >
> > > > To fix this issue, remove nr_bounce from the vmstat_text array.
> > > >
> > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > > > Reported-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> > > > Fixes: 194df9f66db8 ("mm: remove NR_BOUNCE zone stat")
> > > > Cc: stable@vger.kernel.org
> > > > Cc: Christoph Hellwig <hch@lst.de>
> > > > Cc: Hannes Reinecke <hare@suse.de>
> > > > Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> > > > Cc: Jens Axboe <axboe@kernel.dk>
> > >
> > > Is there a way to add a BUILD_BUG_ON to catch a future case like this one?
> >
> > There's
> >
> > BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
> >
> > in vmstat_start().
> >
> > Making it strict != seems to do the trick for my config. But it requires
> > wider testing.
> >
> > I can prepare a patch for that.
>
> There was a strict check before 9d7ea9a297e6 ("mm/vmstat: add helpers to
> get vmstat item names for each enum type"). Not sure if changing != to <
> was intentional.
>
> Konstantin?
I have no clue. Sorry.
>
> --
> Kiryl Shutsemau / Kirill A. Shutemov
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