linux-kernel - Re: [PATCH] proc: report eip and esp for all threads when coredumping

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Date:   Sun, 26 May 2019 21:41:28 +0200
From:   John Ogness <john.ogness@...utronix.de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Jan Luebbe <jlu@...gutronix.de>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andy Lutomirski <luto@...nel.org>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] proc: report eip and esp for all threads when coredumping

Hi Andrew,

On 2019-05-25, Andrew Morton <akpm@...ux-foundation.org> wrote:
> Please send along a signed-off-by: for this?

>From my response:

On 2019-05-25, John Ogness <john.ogness@...utronix.de> wrote:
> AFAICT core_state does not need to be set before the other lines. But
> there may be some side effects that I overlooked!

The changes I showed were more of a suggestion for Jan than an actual
patch. For a signed-off-by I'll need to do some deeper looking to make
sure what I suggested was safe. Also, we probably need a barrier to make
sure the task flag is cleared before setting core_state. Or instead, we
probably should set core_state after releasing the siglock, setting it
where the PF_DUMPCORE flag is set.

It seems to me that checking for a non-NULL core_state and checking for
the PF_DUMPCORE flag are both used throughout the kernel to identify
core dumps in action. So I think it makes sense to set them "at the same
time". (Or perhaps eliminate PF_DUMPCORE altogether and just use a
non-NULL core_state to identify core dumping.)

I will take a closer look at this.

John Ogness