* [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC
[not found] <20230718063328.16140-1-xujianghui@cdjrlc.com>
@ 2023-07-18 6:35 ` sunran001
2023-07-18 17:17 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: sunran001 @ 2023-07-18 6:35 UTC (permalink / raw)
To: dennis, tj, cl, akpm; +Cc: linux-mm, linux-kernel
ERROR: function pcpu_balance_populated called on line 2238 inside lock
on line 2234 but uses GFP_KERNEL
Generated by: scripts/coccinelle/locks/call_kern.cocci
Signed-off-by: Ran Sun <sunran001@208suo.com>
---
mm/percpu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 28e07ede46f6..d8809c7511cd 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2033,7 +2033,7 @@ static void pcpu_balance_free(bool empty_only)
static void pcpu_balance_populated(void)
{
/* gfp flags passed to underlying allocators */
- const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
+ const gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
struct pcpu_chunk *chunk;
int slot, nr_to_pop, ret;
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC
2023-07-18 6:35 ` [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC sunran001
@ 2023-07-18 17:17 ` Andrew Morton
2023-07-20 23:43 ` Baoquan He
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2023-07-18 17:17 UTC (permalink / raw)
To: sunran001; +Cc: dennis, tj, cl, linux-mm, linux-kernel
On Tue, 18 Jul 2023 14:35:11 +0800 sunran001@208suo.com wrote:
> ERROR: function pcpu_balance_populated called on line 2238 inside lock
> on line 2234 but uses GFP_KERNEL
>
> Generated by: scripts/coccinelle/locks/call_kern.cocci
>
> ...
>
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -2033,7 +2033,7 @@ static void pcpu_balance_free(bool empty_only)
> static void pcpu_balance_populated(void)
> {
> /* gfp flags passed to underlying allocators */
> - const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
> + const gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
> struct pcpu_chunk *chunk;
> int slot, nr_to_pop, ret;
I don't believe this warning is correct.
spin_unlock_irq(&pcpu_lock);
ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
cond_resched();
spin_lock_irq(&pcpu_lock);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC
2023-07-18 17:17 ` Andrew Morton
@ 2023-07-20 23:43 ` Baoquan He
0 siblings, 0 replies; 3+ messages in thread
From: Baoquan He @ 2023-07-20 23:43 UTC (permalink / raw)
To: Andrew Morton; +Cc: sunran001, dennis, tj, cl, linux-mm, linux-kernel
On 07/18/23 at 10:17am, Andrew Morton wrote:
> On Tue, 18 Jul 2023 14:35:11 +0800 sunran001@208suo.com wrote:
>
> > ERROR: function pcpu_balance_populated called on line 2238 inside lock
> > on line 2234 but uses GFP_KERNEL
> >
> > Generated by: scripts/coccinelle/locks/call_kern.cocci
> >
> > ...
> >
> > --- a/mm/percpu.c
> > +++ b/mm/percpu.c
> > @@ -2033,7 +2033,7 @@ static void pcpu_balance_free(bool empty_only)
> > static void pcpu_balance_populated(void)
> > {
> > /* gfp flags passed to underlying allocators */
> > - const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
> > + const gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
> > struct pcpu_chunk *chunk;
> > int slot, nr_to_pop, ret;
>
> I don't believe this warning is correct.
Yeah, the warning is false positive. It releases the lock when
requesting memory allocation, then take the lock again.
>
> spin_unlock_irq(&pcpu_lock);
> ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
> cond_resched();
> spin_lock_irq(&pcpu_lock);
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-07-18 6:35 ` [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC sunran001
2023-07-18 17:17 ` Andrew Morton
2023-07-20 23:43 ` Baoquan He
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