From: Andy Lutomirski <luto@amacapital.net>
To: Michel Lespinasse <walken@google.com>
Cc: Ingo Molnar <mingo@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
Hugh Dickins <hughd@google.com>, Jorn_Engel <joern@logfs.org>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/9] Avoid populating unbounded num of ptes with mmap_sem held
Date: Fri, 21 Dec 2012 16:36:21 -0800 [thread overview]
Message-ID: <CALCETrUi4JJSahrDKBARrwGsGE=1RbH8WL4tk1YgDmEowzXtSQ@mail.gmail.com> (raw)
In-Reply-To: <1356050997-2688-1-git-send-email-walken@google.com>
On Thu, Dec 20, 2012 at 4:49 PM, Michel Lespinasse <walken@google.com> wrote:
> We have many vma manipulation functions that are fast in the typical case,
> but can optionally be instructed to populate an unbounded number of ptes
> within the region they work on:
> - mmap with MAP_POPULATE or MAP_LOCKED flags;
> - remap_file_pages() with MAP_NONBLOCK not set or when working on a
> VM_LOCKED vma;
> - mmap_region() and all its wrappers when mlock(MCL_FUTURE) is in effect;
> - brk() when mlock(MCL_FUTURE) is in effect.
>
Something's buggy here. My evil test case is stuck with lots of
threads spinning at 100% system time. Stack traces look like:
[<0000000000000000>] __mlock_vma_pages_range+0x66/0x70
[<0000000000000000>] __mm_populate+0xf9/0x150
[<0000000000000000>] vm_mmap_pgoff+0x9f/0xc0
[<0000000000000000>] sys_mmap_pgoff+0x7e/0x150
[<0000000000000000>] sys_mmap+0x22/0x30
[<0000000000000000>] system_call_fastpath+0x16/0x1b
[<0000000000000000>] 0xffffffffffffffff
perf top says:
38.45% [kernel] [k] __mlock_vma_pages_range
33.04% [kernel] [k] __get_user_pages
28.18% [kernel] [k] __mm_populate
The tasks in question use MCL_FUTURE but not MAP_POPULATE. These
tasks are immune to SIGKILL.
--Andy
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next prev parent reply other threads:[~2012-12-22 0:36 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-21 0:49 Michel Lespinasse
2012-12-21 0:49 ` [PATCH 1/9] mm: make mlockall preserve flags other than VM_LOCKED in def_flags Michel Lespinasse
2012-12-22 4:25 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 2/9] mm: remap_file_pages() fixes Michel Lespinasse
2013-01-03 0:31 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 3/9] mm: introduce mm_populate() for populating new vmas Michel Lespinasse
2013-01-03 2:14 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 4/9] mm: use mm_populate() for blocking remap_file_pages() Michel Lespinasse
2013-01-03 2:25 ` Rik van Riel
2013-03-10 18:55 ` Tommi Rantala
2013-03-11 23:03 ` Andrew Morton
2013-03-12 0:24 ` Michel Lespinasse
2013-03-12 4:23 ` Hillf Danton
2013-03-12 5:01 ` Michel Lespinasse
2013-03-12 20:47 ` Andrew Morton
2012-12-21 0:49 ` [PATCH 5/9] mm: use mm_populate() when adjusting brk with MCL_FUTURE in effect Michel Lespinasse
2013-01-03 2:56 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 6/9] mm: use mm_populate() for mremap() of VM_LOCKED vmas Michel Lespinasse
2013-01-03 5:47 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 7/9] mm: remove flags argument to mmap_region Michel Lespinasse
2013-01-03 5:49 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 8/9] mm: directly use __mlock_vma_pages_range() in find_extend_vma() Michel Lespinasse
2013-01-03 5:50 ` Rik van Riel
2012-12-21 0:49 ` [PATCH 9/9] mm: introduce VM_POPULATE flag to better deal with racy userspace programs Michel Lespinasse
2013-01-03 6:20 ` Rik van Riel
2012-12-21 10:46 ` [PATCH 0/9] Avoid populating unbounded num of ptes with mmap_sem held Michel Lespinasse
2012-12-22 15:02 ` Greg Ungerer
2013-01-23 13:37 ` Greg Ungerer
2012-12-22 0:36 ` Andy Lutomirski [this message]
2012-12-22 0:59 ` Michel Lespinasse
2012-12-22 1:09 ` Andy Lutomirski
2012-12-22 1:59 ` Michel Lespinasse
2012-12-22 2:16 ` Andy Lutomirski
2012-12-22 9:37 ` Michel Lespinasse
2012-12-22 9:45 ` [PATCH 10/9] mm: make do_mmap_pgoff return populate as a size in bytes, not as a bool Michel Lespinasse
2013-01-03 6:21 ` Rik van Riel
2013-01-03 18:54 ` Andy Lutomirski
2013-01-03 18:56 ` [PATCH 0/9] Avoid populating unbounded num of ptes with mmap_sem held Andy Lutomirski
2013-01-04 18:16 ` Andy Lutomirski
2013-01-04 22:58 ` Michel Lespinasse
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