Re: [PATCH 13/12] ksm: fix munlock during exit_mmap deadlock

From: Andrea Arcangeli
Date: Wed Aug 26 2009 - 16:29:27 EST


On Wed, Aug 26, 2009 at 08:57:27PM +0100, Hugh Dickins wrote:
> that might be useful. But KSM_RUN_UNMERGE wouldn't be able to use_mm
> since it's coming from a normal user process - perhaps it should be a
> kill-me-first like swapoff via PF_SWAPOFF.

That would sound just perfect if only there wasn't also a break_cow in
the kksmd context that will trigger page allocation as it can't
takeover the KSM page like it would normally be guaranteed to do for a
cow on a regular anon page mapped readonly in the pte after read
swapin for example. Still for the echo 2 kill me first definitely
makes sense, so maybe we should differentiate the two cases (kksmd and
sysfs).
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