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

From	Vlastimil Babka <vbabka@suse.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH percpu/for-4.7-fixes 2/2] percpu: fix synchronization between synchronous map extension and chunk destruction
Date	2016-05-26 11:50 +0200
Message-ID	<rD05r-4IP-29@gated-at.bofh.it> (permalink)
References	(5 earlier) <rCgch-YP-13@gated-at.bofh.it> <rCmB3-53v-5@gated-at.bofh.it> <rCpSh-7fZ-1@gated-at.bofh.it> <rCrr4-8eY-17@gated-at.bofh.it> <rCJeh-2H3-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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@kernel.org>
> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Reported-by: Vlastimil Babka <vbabka@suse.cz>
> Reported-by: Sasha Levin <sasha.levin@oracle.com>
> Cc: stable@vger.kernel.org # v3.18+
> Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")

Didn't spot any problems this time.

Thanks

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Re: bpf: use-after-free in array_map_alloc Vlastimil Babka <vbabka@suse.cz> - 2016-05-23 14:10 +0200
  Re: bpf: use-after-free in array_map_alloc Tejun Heo <tj@kernel.org> - 2016-05-23 23:40 +0200
    Re: bpf: use-after-free in array_map_alloc Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-05-24 00:20 +0200
    Re: bpf: use-after-free in array_map_alloc Vlastimil Babka <vbabka@suse.cz> - 2016-05-24 10:50 +0200
      Re: bpf: use-after-free in array_map_alloc Tejun Heo <tj@kernel.org> - 2016-05-24 17:40 +0200
        Re: bpf: use-after-free in array_map_alloc Tejun Heo <tj@kernel.org> - 2016-05-24 21:10 +0200
          Re: bpf: use-after-free in array_map_alloc Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-05-24 22:50 +0200
            [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization between  chunk->map_extend_work and chunk destruction Tejun Heo <tj@kernel.org> - 2016-05-25 17:50 +0200
              Re: [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization  between chunk->map_extend_work and chunk destruction Vlastimil Babka <vbabka@suse.cz> - 2016-05-26 11:20 +0200
                Re: [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization  between chunk->map_extend_work and chunk destruction Tejun Heo <tj@kernel.org> - 2016-05-26 21:30 +0200
                Re: [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization  between chunk->map_extend_work and chunk destruction Vlastimil Babka <vbabka@suse.cz> - 2016-05-26 22:50 +0200
            [PATCH percpu/for-4.7-fixes 2/2] percpu: fix synchronization between  synchronous map extension and chunk destruction Tejun Heo <tj@kernel.org> - 2016-05-25 17:50 +0200
              Re: [PATCH percpu/for-4.7-fixes 2/2] percpu: fix synchronization  between synchronous map extension and chunk destruction Vlastimil Babka <vbabka@suse.cz> - 2016-05-26 11:50 +0200

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