Messages in this thread | | | Date | Wed, 14 Mar 2018 15:09:09 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH] percpu: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn() |
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Hello, Andrew.
On Wed, Mar 14, 2018 at 01:56:31PM -0700, Andrew Morton wrote: > It would benefit from a comment explaining why we're doing this (it's > for the oom-killer).
Will add.
> My memory is weak and our documentation is awful. What does > mutex_lock_killable() actually do and how does it differ from > mutex_lock_interruptible()? Userspace tasks can run pcpu_alloc() and I
IIRC, killable listens only to SIGKILL.
> wonder if there's any way in which a userspace-delivered signal can > disrupt another userspace task's memory allocation attempt?
Hmm... maybe. Just honoring SIGKILL *should* be fine but the alloc failure paths might be broken, so there are some risks. Given that the cases where userspace tasks end up allocation percpu memory is pretty limited and/or priviledged (like mount, bpf), I don't think the risks are high tho.
Thanks.
-- tejun
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