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Groups > linux.kernel > #1310905
| From | Vlastimil Babka <vbabka@suse.cz> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition |
| Date | 2016-01-16 08:50 +0100 |
| Message-ID | <qRtMu-1ox-1@gated-at.bofh.it> (permalink) |
| References | <qR79g-2OU-23@gated-at.bofh.it> <qRdHI-7q5-17@gated-at.bofh.it> <qReNs-89q-9@gated-at.bofh.it> <qRqvf-7Hg-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 16.1.2016 5:09, Sergey Senozhatsky wrote:
> On (01/15/16 16:49), Vlastimil Babka wrote:
> [..]
>>
>> Could you please also help making the changelog more clear?
>>
>>>
>>>> + free_obj |= BIT(HANDLE_PIN_BIT);
>>>> record_obj(handle, free_obj);
>>
>> I think record_obj() should use WRITE_ONCE() or something like that.
>> Otherwise the compiler is IMHO allowed to reorder this, i.e. first to assign
>> free_obj to handle, and then add the PIN bit there.
>
> good note.
>
> ... or do both things in record_obj() (per Minchan)
>
> record_obj(handle, obj)
> {
> *(unsigned long)handle = obj & ~(1<<HANDLE_PIN_BIT);
Hmm but that's an unpin, not a pin? A mistake or I'm missing something?
Anyway the compiler can do the same thing here without a WRITE_ONCE().
> }
>
> -ss
>
> --
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Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-15 15:40 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Vlastimil Babka <vbabka@suse.cz> - 2016-01-15 16:50 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-01-16 05:20 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Vlastimil Babka <vbabka@suse.cz> - 2016-01-16 08:50 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-01-16 09:10 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Vlastimil Babka <vbabka@suse.cz> - 2016-01-16 09:20 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-01-16 11:10 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Junil Lee <junil0814.lee@lge.com> - 2016-01-18 02:10 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-18 07:40 +0100
Re: [PATCH v2] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-18 08:10 +0100
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