From: Rik van Riel <riel@surriel.com>
To: Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Roman Gushchin <guro@fb.com>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH 1/1] fork,memcg: alloc_thread_stack_node needs to set tsk->stack
Date: Tue, 18 Jun 2019 21:22:56 -0400 [thread overview]
Message-ID: <e6fe65b301cba1db23d7fefb0031d8eb65574ee7.camel@surriel.com> (raw)
In-Reply-To: <20190619011450.28048-1-aarcange@redhat.com>
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On Tue, 2019-06-18 at 21:14 -0400, Andrea Arcangeli wrote:
> Commit 5eed6f1dff87bfb5e545935def3843edf42800f2 corrected two
> instances, but there was a third instance of this bug.
>
> Without setting tsk->stack, if memcg_charge_kernel_stack fails, it'll
> execute free_thread_stack() on a dangling pointer.
>
> Enterprise kernels are compiled with VMAP_STACK=y so this isn't
> critical, but custom VMAP_STACK=n builds should have some performance
> advantage, with the drawback of risking to fail fork because
> compaction didn't succeed. So as long as VMAP_STACK=n is a supported
> option it's worth fixing it upstream.
>
> Fixes: 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting")
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
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All Rights Reversed.
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next prev parent reply other threads:[~2019-06-19 1:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 1:14 Andrea Arcangeli
2019-06-19 1:22 ` Rik van Riel [this message]
2019-06-19 3:49 ` Roman Gushchin
2019-06-19 5:18 ` Michal Hocko
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