Re: [PATCH] mm: fix page-faults detection in swap-token logic

From: Andrew Morton
Date: Mon Aug 29 2011 - 19:07:07 EST


On Sat, 27 Aug 2011 12:32:01 +0300
Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> wrote:

> After commit v2.6.36-5896-gd065bd8 "mm: retry page fault when blocking on disk transfer"
> we usually wait in page-faults without mmap_sem held, so all swap-token logic was broken,
> because it based on using rwsem_is_locked(&mm->mmap_sem) as sign of in progress page-faults.

If I'm interpreting this correctly, the thrash-handling logic has been
effectively disabled for a year and nobody noticed.

> This patch adds to mm_struct atomic counter of in progress page-faults for mm with swap-token.

We desperately need to delete some code from mm/. This seems like a
great candidate. Someone prove me wrong?
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