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SubjectRe: [PATCH] exec: log when wait_for_dump_helpers aborts due to a signal
On 10/28, Andrew Morton wrote:
>
> Well. Neil's changelog for 61be228a06dc6e8662 is quite nice and tells
> us everything we could possibly want to know, except for why it tests
> sgnal_pending() :(

In short, signal_pending() should not be here. It only reflects the
fact that do_coredump() needs the fixes (and can't resist, I sent the
patch several years ago, but it was ignored ;)

There are 2 reasons. if signal_pending() == T then:

- pipe_wait() is pointless, it won't block. We do not want
a busywait loop.

- And probably even wait_for_dump_helpers() is pointless,
it is quite possible that pipe_write() already failed
before and the reader doesn't know this.

What I think we should do:

- Fix this code, it should not react to signals.

- But! at the same time the explicit SIGKILL should stop
the coredump. It can take a lot of time/resources.

This also makes it oom-killable, and this is important.

- If we dump to the pipe, then perhaps it makes sense to
send a signal to the pipe reader in the latter case, but
this is a bit offtopic.

I'll try to redo my old patches for 3.2 once I have the time. There
are some nasty problems which I forgot, _iirc_ this is not that
trivial.

Oleg.



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