From: Richard Weinberger <richard@nod.at>
To: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: linux-um@lists.infradead.org
Subject: Re: [PATCH] um: Try to avoid kmalloc in signal handling
Date: Fri, 04 Jan 2019 11:33:57 +0100 [thread overview]
Message-ID: <9157944.H6u4diqB1j@blindfold> (raw)
In-Reply-To: <108ad3b6-93ee-5d8c-c1bf-b83e22ff3d3f@cambridgegreys.com>
Am Freitag, 4. Januar 2019, 11:19:46 CET schrieb Anton Ivanov:
> > I fear this is not correct.
> > Think of task switching, if you push something to reg_file[],
> > it is not guaranteed that the same task will run next and pop the item.
> > The order can change.
>
> It should not occur for the signals that map onto IRQ (timer and IO) -
> there it is all kernel.
>
> I cannot trigger that for the other ones, but it may be possible.
We need to be super sure about this.
> IMO we should just bite the bullet and go back to using the stack
> increasing the minimum stack order needed to 1 for 32 bit and to 2 for
> 64 bit.
Increasing the kernel stack just for this is also a huge overhead.
But I never benchmarked it myself.
> x86 if I read it correctly is still using the stack even for the new
> register sets.
Are you sure? I don't think so. The kernel stack is small and the xregset is
huge.
Where did you see this?
Thanks,
//richard
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next prev parent reply other threads:[~2019-01-04 10:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-04 10:05 [PATCH] um: Try to avoid kmalloc in signal handling anton.ivanov
2019-01-04 10:13 ` Richard Weinberger
2019-01-04 10:19 ` Anton Ivanov
2019-01-04 10:33 ` Richard Weinberger [this message]
2019-01-04 10:49 ` Anton Ivanov
2019-01-04 11:31 ` Anton Ivanov
-- strict thread matches above, loose matches on Subject: below --
2019-01-03 16:09 anton.ivanov
2019-01-03 17:13 ` Anton Ivanov
2019-01-03 21:29 ` Anton Ivanov
2019-01-03 21:42 ` Richard Weinberger
2019-01-04 7:07 ` Anton Ivanov
2019-01-04 7:48 ` Anton Ivanov
2019-01-04 15:50 ` Anton Ivanov
2019-01-07 10:07 ` Anton Ivanov
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