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From: Hugh Dickins <hugh@veritas.com>
To: li nux <lnxluv@yahoo.com>
Cc: William Lee Irwin III <wli@holomorphy.com>, linux-kernel@vger.kernel.org
Subject: Re: rmap.c: try_to_unmap_file(): VM_LOCKED not respected
Date: Tue, 14 Jun 2005 14:51:05 +0100 (BST)	[thread overview]
Message-ID: <Pine.LNX.4.61.0506141444040.9201@goblin.wat.veritas.com> (raw)
In-Reply-To: <20050614051405.42342.qmail@web33307.mail.mud.yahoo.com>

On Mon, 13 Jun 2005, li nux wrote:
> My application is using remap_file_pages and mlocks
> those pages.
> So in the code of  try_to_unmap_file (see below),
> I should never reach the call to try_to_unmap_cluster,
> because for those pages VM_LOCKED is always set.
> But, under heavy load I am seeing try_to_unmap_cluster
> is getting called. Stack:
> try_to_unmap_cluster
> try_to_unmap_file
> try_to_unmap
> shrink_list
> 
> Any idea why VM_LOCKED is not being respected ?

Does your application fork occasionally, probably to exec something?
VM_LOCKED is masked off the flags of the child's copy vma (see dup_mmap),
so you might be seeing page reclaim hitting the child in between fork
and exec.  The parent's should remain safely VM_LOCKED as you intended.

Hugh

      parent reply	other threads:[~2005-06-14 13:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-14  5:14 li nux
2005-06-14  5:22 ` William Lee Irwin III
2005-06-14  5:48   ` li nux
2005-06-14  6:31     ` William Lee Irwin III
2005-06-14  7:25       ` li nux
2005-06-14 13:51 ` Hugh Dickins [this message]

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