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From: Yang Shi <yang.shi@linux.alibaba.com>
To: Michal Hocko <mhocko@kernel.org>,
	Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: willy@infradead.org, akpm@linux-foundation.org,
	peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
	alexander.shishkin@linux.intel.com, jolsa@redhat.com,
	namhyung@kernel.org, tglx@linutronix.de, hpa@zytor.com,
	linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC v3 PATCH 5/5] x86: check VM_DEAD flag in page fault
Date: Mon, 2 Jul 2018 10:24:27 -0700	[thread overview]
Message-ID: <6fd4eb3d-ef66-7a37-4adb-05c22ac51d95@linux.alibaba.com> (raw)
In-Reply-To: <20180702133733.GU19043@dhcp22.suse.cz>



On 7/2/18 6:37 AM, Michal Hocko wrote:
> On Mon 02-07-18 15:33:11, Laurent Dufour wrote:
>>
>> On 02/07/2018 14:45, Michal Hocko wrote:
>>> On Mon 02-07-18 14:26:09, Laurent Dufour wrote:
>>>> On 02/07/2018 14:15, Michal Hocko wrote:
> [...]
>>>>> We already do have a model for that. Have a look at MMF_UNSTABLE.
>>>> MMF_UNSTABLE is a mm's flag, here this is a VMA's flag which is checked.
>>> Yeah, and we have the VMA ready for all places where we do check the
>>> flag. check_stable_address_space can be made to get vma rather than mm.
>> Yeah, this would have been more efficient to check that flag at the beginning
>> of the page fault handler rather than the end, but this way it will be easier
>> to handle the speculative page fault too ;)
> The thing is that it doesn't really need to be called earlier. You are
> not risking data corruption on file backed mappings.

OK, I just think it could save a few cycles to check the flag earlier.

If nobody think it is necessary, we definitely could re-use 
check_stable_address_space(), just return VM_FAULT_SIGSEGV for VM_DEAD 
vma, and check for both shared and non-shared.

Thanks,
Yang

>

  reply	other threads:[~2018-07-02 17:24 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-29 22:39 [RFC v3 PATCH 0/5] mm: zap pages with read mmap_sem in munmap for large mapping Yang Shi
2018-06-29 22:39 ` [RFC v3 PATCH 1/5] uprobes: make vma_has_uprobes non-static Yang Shi
2018-06-29 22:39 ` [RFC v3 PATCH 2/5] mm: introduce VM_DEAD flag Yang Shi
2018-07-02 13:40   ` Michal Hocko
2018-06-29 22:39 ` [RFC v3 PATCH 3/5] mm: refactor do_munmap() to extract the common part Yang Shi
2018-07-02 13:42   ` Michal Hocko
2018-07-02 16:59     ` Yang Shi
2018-07-02 17:58       ` Michal Hocko
2018-07-02 18:02         ` Yang Shi
2018-06-29 22:39 ` [RFC v3 PATCH 4/5] mm: mmap: zap pages with read mmap_sem for large mapping Yang Shi
2018-06-30  1:28   ` Andrew Morton
2018-06-30  2:10     ` Yang Shi
2018-06-30  1:35   ` Andrew Morton
2018-06-30  2:28     ` Yang Shi
2018-06-30  3:15       ` Andrew Morton
2018-06-30  4:26         ` Yang Shi
2018-07-03  0:01           ` Yang Shi
2018-07-02 14:05         ` Michal Hocko
2018-07-02 20:48           ` Andrew Morton
2018-07-03  6:09             ` Michal Hocko
2018-07-03 16:53               ` Yang Shi
2018-07-03 18:22               ` Yang Shi
2018-07-04  8:13                 ` Michal Hocko
2018-07-02 12:33   ` Kirill A. Shutemov
2018-07-02 12:49     ` Michal Hocko
2018-07-03  8:12       ` Kirill A. Shutemov
2018-07-03  8:27         ` Michal Hocko
2018-07-03  9:19           ` Kirill A. Shutemov
2018-07-03 11:34             ` Michal Hocko
2018-07-03 12:14               ` Kirill A. Shutemov
2018-07-03 17:00                 ` Yang Shi
2018-07-02 17:19     ` Yang Shi
2018-07-03  8:07       ` Kirill A. Shutemov
2018-07-02 13:53   ` Michal Hocko
2018-07-02 17:07     ` Yang Shi
2018-06-29 22:39 ` [RFC v3 PATCH 5/5] x86: check VM_DEAD flag in page fault Yang Shi
2018-07-02  8:45   ` Laurent Dufour
2018-07-02 12:15     ` Michal Hocko
2018-07-02 12:26       ` Laurent Dufour
2018-07-02 12:45         ` Michal Hocko
2018-07-02 13:33           ` Laurent Dufour
2018-07-02 13:37             ` Michal Hocko
2018-07-02 17:24               ` Yang Shi [this message]
2018-07-02 17:57                 ` Michal Hocko
2018-07-02 18:10                   ` Yang Shi
2018-07-03  6:17                     ` Michal Hocko
2018-07-03 16:50                       ` Yang Shi
2018-07-02 13:39 ` [RFC v3 PATCH 0/5] mm: zap pages with read mmap_sem in munmap for large mapping Michal Hocko

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