From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michal Hocko <mhocko@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] oom-reaper: use madvise_dontneed() instead of unmap_page_range()
Date: Mon, 19 Dec 2016 20:39:24 +0900 [thread overview]
Message-ID: <e9dd55e8-4cf0-0e91-ddeb-3004ca8fc611@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20161216141556.75130-4-kirill.shutemov@linux.intel.com>
On 2016/12/16 23:15, Kirill A. Shutemov wrote:
> Logic on whether we can reap pages from the VMA should match what we
> have in madvise_dontneed(). In particular, we should skip, VM_PFNMAP
> VMAs, but we don't now.
>
> Let's just call madvise_dontneed() from __oom_reap_task_mm(), so we
> won't need to sync the logic in the future.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> mm/internal.h | 7 +++----
> mm/madvise.c | 2 +-
> mm/memory.c | 2 +-
> mm/oom_kill.c | 15 ++-------------
> 4 files changed, 7 insertions(+), 19 deletions(-)
madvise_dontneed() calls zap_page_range().
zap_page_range() calls mmu_notifier_invalidate_range_start().
mmu_notifier_invalidate_range_start() calls __mmu_notifier_invalidate_range_start().
__mmu_notifier_invalidate_range_start() calls srcu_read_lock()/srcu_read_unlock().
This means that madvise_dontneed() might sleep.
I don't know what individual notifier will do, but for example
static const struct mmu_notifier_ops i915_gem_userptr_notifier = {
.invalidate_range_start = i915_gem_userptr_mn_invalidate_range_start,
};
i915_gem_userptr_mn_invalidate_range_start() calls flush_workqueue()
which means that we can OOM livelock if work item involves memory allocation.
Some of other notifiers call mutex_lock()/mutex_unlock().
Even if none of currently in-tree notifier users are blocked on memory
allocation, I think it is not guaranteed that future changes/users won't be
blocked on memory allocation.
next prev parent reply other threads:[~2016-12-19 11:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-16 14:15 [PATCH 1/4] mm: drop zap_details::ignore_dirty Kirill A. Shutemov
2016-12-16 14:15 ` [PATCH 2/4] mm: drop zap_details::check_swap_entries Kirill A. Shutemov
2016-12-19 14:29 ` Michal Hocko
2016-12-16 14:15 ` [PATCH 3/4] mm: drop unused argument of zap_page_range() Kirill A. Shutemov
2016-12-16 17:02 ` kbuild test robot
2016-12-19 14:35 ` Michal Hocko
2016-12-16 14:15 ` [PATCH 4/4] oom-reaper: use madvise_dontneed() instead of unmap_page_range() Kirill A. Shutemov
2016-12-16 16:10 ` kbuild test robot
2016-12-16 16:45 ` kbuild test robot
2016-12-19 11:39 ` Tetsuo Handa [this message]
2016-12-19 14:00 ` Michal Hocko
2016-12-19 14:38 ` Michal Hocko
2016-12-19 14:22 ` [PATCH 1/4] mm: drop zap_details::ignore_dirty Michal Hocko
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