Re: [PATCH 1/1] signals: introduce send_sigkill() helper

From: Oleg Nesterov
Date: Sun Jun 13 2010 - 11:31:10 EST

Andrew, please drop


I am stupid.

On 06/10, Oleg Nesterov wrote:
> Cleanup, no functional changes.
> There are a lot of buggy SIGKILL users in kernel. For example, almost
> every force_sig(SIGKILL) is wrong. force_sig() is not safe, it assumes
> that the task has the valid ->sighand, and in general it should be used
> only for synchronous signals. send_sig(SIGKILL, p, 1) or
> send_xxx(SEND_SIG_FORCED/SEND_SIG_PRIV) is not right too but this is not
> immediately obvious.
> The only way to correctly send SIGKILL is send_sig_info(SEND_SIG_NOINFO)

No, SEND_SIG_NOINFO doesn't work too. Oh, can't understand what I was
thinking about. current is the random task, but send_signal() checks
if the caller is from-parent-ns.

> Note: we need more cleanups here, this is only the first change.

We need the cleanups first. Until then oom-killer has to use force_sig()
if we want to kill the SIGNAL_UNKILLABLE tasks too.


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