* [PATCH] mm, vmstat: Make sure mutex is a global static
@ 2017-11-07 21:38 Kees Cook
2017-11-08 7:43 ` Vlastimil Babka
2017-11-09 1:10 ` kemi
0 siblings, 2 replies; 6+ messages in thread
From: Kees Cook @ 2017-11-07 21:38 UTC (permalink / raw)
To: Andrew Morton, Jesper Dangaard Brouer
Cc: Dave Hansen, Ying Huang, Vlastimil Babka, Michal Hocko, linux-kernel
The mutex in sysctl_vm_numa_stat_handler() needs to be a global static, not
a stack variable, otherwise it doesn't serve any purpose. Also, reading the
file with CONFIG_LOCKDEP=y will complain:
[ 63.258593] INFO: trying to register non-static key.
[ 63.259113] the code is fine but needs lockdep annotation.
[ 63.259596] turning off the locking correctness validator.
[ 63.260073] CPU: 1 PID: 4102 Comm: perl Not tainted 4.14.0-rc8-next-20171107+ #419
[ 63.260769] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 63.261570] Call Trace:
[ 63.261783] dump_stack+0x5f/0x86
[ 63.262062] register_lock_class+0xe4/0x550
[ 63.262408] ? __lock_acquire+0x308/0x1170
[ 63.262746] __lock_acquire+0x7e/0x1170
[ 63.263063] lock_acquire+0x9d/0x1d0
[ 63.263363] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.263777] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.264192] __mutex_lock+0xb8/0x9a0
[ 63.264488] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.264942] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.265398] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.265840] sysctl_vm_numa_stat_handler+0x8f/0x2d0
[ 63.266270] proc_sys_call_handler+0xe3/0x100
[ 63.266655] __vfs_read+0x33/0x1b0
[ 63.266957] vfs_read+0xa6/0x150
[ 63.267244] SyS_read+0x55/0xc0
[ 63.267525] do_syscall_64+0x56/0x140
[ 63.267850] entry_SYSCALL64_slow_path+0x25/0x25
Fixes: 920d5f77d1a25 ("mm, sysctl: make NUMA stats configurable")
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
mm/vmstat.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index e0593434fd58..40b2db6db6b1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -72,11 +72,12 @@ static void invalid_numa_statistics(void)
zero_global_numa_counters();
}
+static DEFINE_MUTEX(vm_numa_stat_lock);
+
int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
int ret, oldval;
- DEFINE_MUTEX(vm_numa_stat_lock);
mutex_lock(&vm_numa_stat_lock);
if (write)
--
2.7.4
--
Kees Cook
Pixel Security
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] mm, vmstat: Make sure mutex is a global static
2017-11-07 21:38 [PATCH] mm, vmstat: Make sure mutex is a global static Kees Cook
@ 2017-11-08 7:43 ` Vlastimil Babka
2017-11-08 14:20 ` Michal Hocko
2017-11-08 15:21 ` Kees Cook
2017-11-09 1:10 ` kemi
1 sibling, 2 replies; 6+ messages in thread
From: Vlastimil Babka @ 2017-11-08 7:43 UTC (permalink / raw)
To: Kees Cook, Andrew Morton, Jesper Dangaard Brouer
Cc: Dave Hansen, Ying Huang, Michal Hocko, linux-kernel
On 11/07/2017 10:38 PM, Kees Cook wrote:
> The mutex in sysctl_vm_numa_stat_handler() needs to be a global static, not
> a stack variable, otherwise it doesn't serve any purpose. Also, reading the
> file with CONFIG_LOCKDEP=y will complain:
Oops, good catch.
> [ 63.258593] INFO: trying to register non-static key.
> [ 63.259113] the code is fine but needs lockdep annotation.
> [ 63.259596] turning off the locking correctness validator.
> [ 63.260073] CPU: 1 PID: 4102 Comm: perl Not tainted 4.14.0-rc8-next-20171107+ #419
> [ 63.260769] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> [ 63.261570] Call Trace:
> [ 63.261783] dump_stack+0x5f/0x86
> [ 63.262062] register_lock_class+0xe4/0x550
> [ 63.262408] ? __lock_acquire+0x308/0x1170
> [ 63.262746] __lock_acquire+0x7e/0x1170
> [ 63.263063] lock_acquire+0x9d/0x1d0
> [ 63.263363] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.263777] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.264192] __mutex_lock+0xb8/0x9a0
> [ 63.264488] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.264942] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.265398] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.265840] sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.266270] proc_sys_call_handler+0xe3/0x100
> [ 63.266655] __vfs_read+0x33/0x1b0
> [ 63.266957] vfs_read+0xa6/0x150
> [ 63.267244] SyS_read+0x55/0xc0
> [ 63.267525] do_syscall_64+0x56/0x140
> [ 63.267850] entry_SYSCALL64_slow_path+0x25/0x25
>
> Fixes: 920d5f77d1a25 ("mm, sysctl: make NUMA stats configurable")
Note that this hash is specific to particular next-$DATE as mmotm is
reimported each day.
> Cc: Jesper Dangaard Brouer <brouer@redhat.com>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Ying Huang <ying.huang@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Michal Hocko <mhocko@suse.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> mm/vmstat.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index e0593434fd58..40b2db6db6b1 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -72,11 +72,12 @@ static void invalid_numa_statistics(void)
> zero_global_numa_counters();
> }
>
> +static DEFINE_MUTEX(vm_numa_stat_lock);
> +
> int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
> void __user *buffer, size_t *length, loff_t *ppos)
> {
> int ret, oldval;
> - DEFINE_MUTEX(vm_numa_stat_lock);
Yeah it was Michal who suggested scoping the mutex here instead of
global scope, but I think he didn't mean to remove the 'static'
qualifier, and we both missed that in the review :(
So the scope under sysctl_vm_numa_stat_handler() should be okay, just
with the 'static' added.
>
> mutex_lock(&vm_numa_stat_lock);
> if (write)
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, vmstat: Make sure mutex is a global static
2017-11-08 7:43 ` Vlastimil Babka
@ 2017-11-08 14:20 ` Michal Hocko
2017-11-08 15:21 ` Kees Cook
1 sibling, 0 replies; 6+ messages in thread
From: Michal Hocko @ 2017-11-08 14:20 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Kees Cook, Andrew Morton, Jesper Dangaard Brouer, Dave Hansen,
Ying Huang, linux-kernel
On Wed 08-11-17 08:43:44, Vlastimil Babka wrote:
> On 11/07/2017 10:38 PM, Kees Cook wrote:
[...]
> > +static DEFINE_MUTEX(vm_numa_stat_lock);
> > +
> > int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
> > void __user *buffer, size_t *length, loff_t *ppos)
> > {
> > int ret, oldval;
> > - DEFINE_MUTEX(vm_numa_stat_lock);
>
> Yeah it was Michal who suggested scoping the mutex here instead of
> global scope, but I think he didn't mean to remove the 'static'
> qualifier, and we both missed that in the review :(
> So the scope under sysctl_vm_numa_stat_handler() should be okay, just
> with the 'static' added.
exactly! Sorry that I've missed the missing static and thanks for
catching that Kees.
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, vmstat: Make sure mutex is a global static
2017-11-08 7:43 ` Vlastimil Babka
2017-11-08 14:20 ` Michal Hocko
@ 2017-11-08 15:21 ` Kees Cook
2017-11-09 7:50 ` Michal Hocko
1 sibling, 1 reply; 6+ messages in thread
From: Kees Cook @ 2017-11-08 15:21 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Andrew Morton, Jesper Dangaard Brouer, Dave Hansen, Ying Huang,
Michal Hocko, LKML
On Tue, Nov 7, 2017 at 11:43 PM, Vlastimil Babka <vbabka@suse.cz> wrote:
> On 11/07/2017 10:38 PM, Kees Cook wrote:
>> The mutex in sysctl_vm_numa_stat_handler() needs to be a global static, not
>> a stack variable, otherwise it doesn't serve any purpose. Also, reading the
>> file with CONFIG_LOCKDEP=y will complain:
>
> Oops, good catch.
>
>> [ 63.258593] INFO: trying to register non-static key.
>> [ 63.259113] the code is fine but needs lockdep annotation.
>> [ 63.259596] turning off the locking correctness validator.
>> [ 63.260073] CPU: 1 PID: 4102 Comm: perl Not tainted 4.14.0-rc8-next-20171107+ #419
>> [ 63.260769] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
>> [ 63.261570] Call Trace:
>> [ 63.261783] dump_stack+0x5f/0x86
>> [ 63.262062] register_lock_class+0xe4/0x550
>> [ 63.262408] ? __lock_acquire+0x308/0x1170
>> [ 63.262746] __lock_acquire+0x7e/0x1170
>> [ 63.263063] lock_acquire+0x9d/0x1d0
>> [ 63.263363] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.263777] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.264192] __mutex_lock+0xb8/0x9a0
>> [ 63.264488] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.264942] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.265398] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.265840] sysctl_vm_numa_stat_handler+0x8f/0x2d0
>> [ 63.266270] proc_sys_call_handler+0xe3/0x100
>> [ 63.266655] __vfs_read+0x33/0x1b0
>> [ 63.266957] vfs_read+0xa6/0x150
>> [ 63.267244] SyS_read+0x55/0xc0
>> [ 63.267525] do_syscall_64+0x56/0x140
>> [ 63.267850] entry_SYSCALL64_slow_path+0x25/0x25
>>
>> Fixes: 920d5f77d1a25 ("mm, sysctl: make NUMA stats configurable")
>
> Note that this hash is specific to particular next-$DATE as mmotm is
> reimported each day.
Ah yes, duh. :)
>
>> Cc: Jesper Dangaard Brouer <brouer@redhat.com>
>> Cc: Dave Hansen <dave.hansen@intel.com>
>> Cc: Ying Huang <ying.huang@intel.com>
>> Cc: Vlastimil Babka <vbabka@suse.cz>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>> mm/vmstat.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/vmstat.c b/mm/vmstat.c
>> index e0593434fd58..40b2db6db6b1 100644
>> --- a/mm/vmstat.c
>> +++ b/mm/vmstat.c
>> @@ -72,11 +72,12 @@ static void invalid_numa_statistics(void)
>> zero_global_numa_counters();
>> }
>>
>> +static DEFINE_MUTEX(vm_numa_stat_lock);
>> +
>> int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
>> void __user *buffer, size_t *length, loff_t *ppos)
>> {
>> int ret, oldval;
>> - DEFINE_MUTEX(vm_numa_stat_lock);
>
> Yeah it was Michal who suggested scoping the mutex here instead of
> global scope, but I think he didn't mean to remove the 'static'
> qualifier, and we both missed that in the review :(
> So the scope under sysctl_vm_numa_stat_handler() should be okay, just
> with the 'static' added.
That part is a matter of taste, I guess. :) But yes, static is important.
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] mm, vmstat: Make sure mutex is a global static
2017-11-08 15:21 ` Kees Cook
@ 2017-11-09 7:50 ` Michal Hocko
0 siblings, 0 replies; 6+ messages in thread
From: Michal Hocko @ 2017-11-09 7:50 UTC (permalink / raw)
To: Kees Cook
Cc: Vlastimil Babka, Andrew Morton, Jesper Dangaard Brouer,
Dave Hansen, Ying Huang, LKML
On Wed 08-11-17 07:21:20, Kees Cook wrote:
> On Tue, Nov 7, 2017 at 11:43 PM, Vlastimil Babka <vbabka@suse.cz> wrote:
> > On 11/07/2017 10:38 PM, Kees Cook wrote:
[...]
> >> +static DEFINE_MUTEX(vm_numa_stat_lock);
> >> +
> >> int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
> >> void __user *buffer, size_t *length, loff_t *ppos)
> >> {
> >> int ret, oldval;
> >> - DEFINE_MUTEX(vm_numa_stat_lock);
> >
> > Yeah it was Michal who suggested scoping the mutex here instead of
> > global scope, but I think he didn't mean to remove the 'static'
> > qualifier, and we both missed that in the review :(
> > So the scope under sysctl_vm_numa_stat_handler() should be okay, just
> > with the 'static' added.
>
> That part is a matter of taste, I guess. :) But yes, static is important.
The primary reason I prefer function scope lock is that it is less
tempting to reuse the lock for something else that way. But this is
hardly something to insist on. So I am ok with the file scope as well.
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: mm, vmstat: Make sure mutex is a global static
2017-11-07 21:38 [PATCH] mm, vmstat: Make sure mutex is a global static Kees Cook
2017-11-08 7:43 ` Vlastimil Babka
@ 2017-11-09 1:10 ` kemi
1 sibling, 0 replies; 6+ messages in thread
From: kemi @ 2017-11-09 1:10 UTC (permalink / raw)
To: Kees Cook, Andrew Morton, Jesper Dangaard Brouer
Cc: Dave Hansen, Ying Huang, Vlastimil Babka, Michal Hocko, linux-kernel
On 2017年11月08日 05:38, Kees Cook wrote:
> The mutex in sysctl_vm_numa_stat_handler() needs to be a global static, not
> a stack variable, otherwise it doesn't serve any purpose. Also, reading the
> file with CONFIG_LOCKDEP=y will complain:
>
It's my mistake. Kees, thanks for catching it.
> [ 63.258593] INFO: trying to register non-static key.
> [ 63.259113] the code is fine but needs lockdep annotation.
> [ 63.259596] turning off the locking correctness validator.
> [ 63.260073] CPU: 1 PID: 4102 Comm: perl Not tainted 4.14.0-rc8-next-20171107+ #419
> [ 63.260769] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> [ 63.261570] Call Trace:
> [ 63.261783] dump_stack+0x5f/0x86
> [ 63.262062] register_lock_class+0xe4/0x550
> [ 63.262408] ? __lock_acquire+0x308/0x1170
> [ 63.262746] __lock_acquire+0x7e/0x1170
> [ 63.263063] lock_acquire+0x9d/0x1d0
> [ 63.263363] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.263777] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.264192] __mutex_lock+0xb8/0x9a0
> [ 63.264488] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.264942] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.265398] ? sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.265840] sysctl_vm_numa_stat_handler+0x8f/0x2d0
> [ 63.266270] proc_sys_call_handler+0xe3/0x100
> [ 63.266655] __vfs_read+0x33/0x1b0
> [ 63.266957] vfs_read+0xa6/0x150
> [ 63.267244] SyS_read+0x55/0xc0
> [ 63.267525] do_syscall_64+0x56/0x140
> [ 63.267850] entry_SYSCALL64_slow_path+0x25/0x25
>
> Fixes: 920d5f77d1a25 ("mm, sysctl: make NUMA stats configurable")
> Cc: Jesper Dangaard Brouer <brouer@redhat.com>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Ying Huang <ying.huang@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Michal Hocko <mhocko@suse.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> mm/vmstat.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index e0593434fd58..40b2db6db6b1 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -72,11 +72,12 @@ static void invalid_numa_statistics(void)
> zero_global_numa_counters();
> }
>
> +static DEFINE_MUTEX(vm_numa_stat_lock);
> +
> int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
> void __user *buffer, size_t *length, loff_t *ppos)
> {
> int ret, oldval;
> - DEFINE_MUTEX(vm_numa_stat_lock);
>
> mutex_lock(&vm_numa_stat_lock);
> if (write)
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-11-09 7:50 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-11-07 21:38 [PATCH] mm, vmstat: Make sure mutex is a global static Kees Cook
2017-11-08 7:43 ` Vlastimil Babka
2017-11-08 14:20 ` Michal Hocko
2017-11-08 15:21 ` Kees Cook
2017-11-09 7:50 ` Michal Hocko
2017-11-09 1:10 ` kemi
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