From: Oleg Nesterov <oleg@redhat.com>
Date: Thu, 9 Oct 2014 22:25:41 +0000 (-0700)
Subject: fs/proc/task_mmu.c: reintroduce m->version logic
X-Git-Tag: fixes-against-v3.18-rc2~137^2~130
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b8c20a9b85b057c850f63ee4c63531a356d8596a;p=pandora-kernel.git

fs/proc/task_mmu.c: reintroduce m->version logic

Add the "last_addr" optimization back. Like before, every ->show()
method checks !seq_overflow() and sets m->version = vma->vm_start.

However, it also checks that m_next_vma(vma) != NULL, otherwise it
sets m->version = -1 for the lockless "EOF" fast-path in m_start().

m_start() can simply do find_vma() + m_next_vma() if last_addr is
not zero, the code looks clear and simple and this case is clearly
separated from "scan vmas" path.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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