From: Andrew Morton <akpm@linux-foundation.org>
To: Haggai Eran <haggaie@mellanox.com>
Cc: linux-mm@kvack.org, Andrea Arcangeli <aarcange@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Shachar Raindel <raindel@mellanox.com>,
Sagi Grimberg <sagig@mellanox.com>,
Or Gerlitz <ogerlitz@mellanox.com>
Subject: Re: [PATCH V1 2/2] mm: Wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end
Date: Tue, 4 Sep 2012 15:07:54 -0700 [thread overview]
Message-ID: <20120904150754.ea574c4e.akpm@linux-foundation.org> (raw)
In-Reply-To: <1346748081-1652-3-git-send-email-haggaie@mellanox.com>
On Tue, 4 Sep 2012 11:41:21 +0300
Haggai Eran <haggaie@mellanox.com> wrote:
> In order to allow sleeping during invalidate_page mmu notifier calls, we
> need to avoid calling when holding the PT lock. In addition to its
> direct calls, invalidate_page can also be called as a substitute for a
> change_pte call, in case the notifier client hasn't implemented
> change_pte.
>
> This patch drops the invalidate_page call from change_pte, and instead
> wraps all calls to change_pte with invalidate_range_start and
> invalidate_range_end calls.
>
> Note that change_pte still cannot sleep after this patch, and that
> clients implementing change_pte should not take action on it in case the
> number of outstanding invalidate_range_start calls is larger than one,
> otherwise they might miss a later invalidation.
>
> ...
>
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -145,6 +145,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
> /* For try_to_free_swap() and munlock_vma_page() below */
> lock_page(page);
>
> + mmu_notifier_invalidate_range_start(mm, addr, addr + PAGE_SIZE);
> err = -EAGAIN;
> ptep = page_check_address(page, mm, addr, &ptl, 0);
> if (!ptep)
> @@ -173,6 +174,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
>
> err = 0;
> unlock:
> + mmu_notifier_invalidate_range_end(mm, addr, addr + PAGE_SIZE);
> unlock_page(page);
> return err;
> }
Again, now I have to apply the patch and peer at the code to work out
whether `addr' got changed anywhere between these two calls. And I
somehow need to ensure that `addr' will not get modified in the future
and I can't do that!
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next prev parent reply other threads:[~2012-09-04 22:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-04 8:41 [PATCH V1 0/2] Enable clients to schedule in mmu_notifier methods Haggai Eran
2012-09-04 8:41 ` [PATCH V1 1/2] mm: Move all mmu notifier invocations to be done outside the PT lock Haggai Eran
2012-09-04 22:07 ` Andrew Morton
2012-09-06 14:34 ` [PATCH V2 0/2] Enable clients to schedule in mmu_notifier methods Haggai Eran
2012-09-06 14:34 ` [PATCH V2 1/2] mm: Move all mmu notifier invocations to be done outside the PT lock Haggai Eran
2012-09-06 14:34 ` [PATCH V2 2/2] mm: Wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end Haggai Eran
2012-09-06 20:08 ` [PATCH V2 0/2] Enable clients to schedule in mmu_notifier methods Andrew Morton
2012-09-04 8:41 ` [PATCH V1 2/2] mm: Wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end Haggai Eran
2012-09-04 22:07 ` Andrew Morton [this message]
2012-09-04 22:06 ` [PATCH V1 0/2] Enable clients to schedule in mmu_notifier methods Andrew Morton
2012-09-05 12:55 ` Avi Kivity
2012-09-05 14:01 ` Haggai Eran
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