From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>,
willy@infradead.org, ldufour@linux.vnet.ibm.com,
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 4/5] mm: mmap: zap pages with read mmap_sem for large mapping
Date: Mon, 2 Jul 2018 13:48:45 -0700 [thread overview]
Message-ID: <20180702134845.c4f536dead5374b443e24270@linux-foundation.org> (raw)
In-Reply-To: <20180702140502.GZ19043@dhcp22.suse.cz>
On Mon, 2 Jul 2018 16:05:02 +0200 Michal Hocko <mhocko@kernel.org> wrote:
> On Fri 29-06-18 20:15:47, Andrew Morton wrote:
> [...]
> > Would one of your earlier designs have addressed all usecases? I
> > expect the dumb unmap-a-little-bit-at-a-time approach would have?
>
> It has been already pointed out that this will not work.
I said "one of". There were others.
> You simply
> cannot drop the mmap_sem during unmap because another thread could
> change the address space under your feet. So you need some form of
> VM_DEAD and handle concurrent and conflicting address space operations.
Unclear that this is a problem. If a thread does an unmap of a range
of virtual address space, there's no guarantee that upon return some
other thread has not already mapped new stuff into that address range.
So what's changed?
next prev parent reply other threads:[~2018-07-02 20:48 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 [this message]
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
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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