Re: [PATCH percpu/for-4.7-fixes 2/2] percpu: fix synchronization between synchronous map extension and chunk destruction

[Vlastimil Babka]

On 05/25/2016 05:45 PM, Tejun Heo wrote:
> For non-atomic allocations, pcpu_alloc() can try to extend the area
> map synchronously after dropping pcpu_lock; however, the extension
> wasn't synchronized against chunk destruction and the chunk might get
> freed while extension is in progress.
>
> This patch fixes the bug by putting most of non-atomic allocations
> under pcpu_alloc_mutex to synchronize against pcpu_balance_work which
> is responsible for async chunk management including destruction.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
> Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
> Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v3.18+
> Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")

Didn't spot any problems this time.

Thanks