2022-02-22 04:40:08

by Andrzej Hajda

Subject: [PATCH v3 07/11] lib/ref_tracker: remove warnings in case of allocation failure

Library can handle allocation failures. To avoid allocation warnings
__GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been
replaced with GFP_NOWAIT in case of stack allocation on tracker free
call.

Signed-off-by: Andrzej Hajda <[email protected]>
---
lib/ref_tracker.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 2ef4596b6b36f..cae4498fcfd70 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -189,7 +189,7 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
unsigned long entries[REF_TRACKER_STACK_ENTRIES];
struct ref_tracker *tracker;
unsigned int nr_entries;
- gfp_t gfp_mask = gfp;
+ gfp_t gfp_mask = gfp | __GFP_NOWARN;
unsigned long flags;

WARN_ON_ONCE(dir->dead);
@@ -237,7 +237,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
return -EEXIST;
}
nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
- stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
+ stack_handle = stack_depot_save(entries, nr_entries,
+ GFP_NOWAIT | __GFP_NOWARN);

spin_lock_irqsave(&dir->lock, flags);
if (tracker->dead) {
--
2.25.1

2022-02-22 05:49:28

by Eric Dumazet

Subject: Re: [PATCH v3 07/11] lib/ref_tracker: remove warnings in case of allocation failure

On Mon, Feb 21, 2022 at 3:26 PM Andrzej Hajda <[email protected]> wrote:
>
> Library can handle allocation failures. To avoid allocation warnings
> __GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been
> replaced with GFP_NOWAIT in case of stack allocation on tracker free
> call.
>
> Signed-off-by: Andrzej Hajda <[email protected]>
> ---
> lib/ref_tracker.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
> index 2ef4596b6b36f..cae4498fcfd70 100644
> --- a/lib/ref_tracker.c
> +++ b/lib/ref_tracker.c
> @@ -189,7 +189,7 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
> unsigned long entries[REF_TRACKER_STACK_ENTRIES];
> struct ref_tracker *tracker;
> unsigned int nr_entries;
> - gfp_t gfp_mask = gfp;
> + gfp_t gfp_mask = gfp | __GFP_NOWARN;

SGTM

> unsigned long flags;
>
> WARN_ON_ONCE(dir->dead);
> @@ -237,7 +237,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
> return -EEXIST;
> }
> nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
> - stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
> + stack_handle = stack_depot_save(entries, nr_entries,
> + GFP_NOWAIT | __GFP_NOWARN);

Last time I looked at this, __GFP_NOWARN was enforced in __stack_depot_save()

>
> spin_lock_irqsave(&dir->lock, flags);
> if (tracker->dead) {
> --
> 2.25.1
>

2022-02-22 13:18:05

by Andrzej Hajda

Subject: Re: [PATCH v3 07/11] lib/ref_tracker: remove warnings in case of allocation failure

On 22.02.2022 00:54, Eric Dumazet wrote:
> On Mon, Feb 21, 2022 at 3:26 PM Andrzej Hajda <[email protected]> wrote:
>> Library can handle allocation failures. To avoid allocation warnings
>> __GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been
>> replaced with GFP_NOWAIT in case of stack allocation on tracker free
>> call.
>>
>> Signed-off-by: Andrzej Hajda <[email protected]>
>> ---
>> lib/ref_tracker.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
>> index 2ef4596b6b36f..cae4498fcfd70 100644
>> --- a/lib/ref_tracker.c
>> +++ b/lib/ref_tracker.c
>> @@ -189,7 +189,7 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
>> unsigned long entries[REF_TRACKER_STACK_ENTRIES];
>> struct ref_tracker *tracker;
>> unsigned int nr_entries;
>> - gfp_t gfp_mask = gfp;
>> + gfp_t gfp_mask = gfp | __GFP_NOWARN;
> SGTM
>
>> unsigned long flags;
>>
>> WARN_ON_ONCE(dir->dead);
>> @@ -237,7 +237,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
>> return -EEXIST;
>> }
>> nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
>> - stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
>> + stack_handle = stack_depot_save(entries, nr_entries,
>> + GFP_NOWAIT | __GFP_NOWARN);
> Last time I looked at this, __GFP_NOWARN was enforced in __stack_depot_save()

You are right, however I am not sure if we should count on unexpected
(at least for me) and undocumented behavior.
Currently we do not need to rely on some hidden feature.

Regards
Andrzej

>
>> spin_lock_irqsave(&dir->lock, flags);
>> if (tracker->dead) {
>> --
>> 2.25.1
>>