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From: Matthew Wilcox <willy@infradead.org>
To: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Michal Hocko <mhocko@kernel.org>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/8] mm: mmap: unmap large mapping by section
Date: Wed, 21 Mar 2018 15:46:31 -0700 [thread overview]
Message-ID: <20180321224631.GB3969@bombadil.infradead.org> (raw)
In-Reply-To: <f057a634-7e0a-1b51-eede-dcb6f128b18e@linux.alibaba.com>
On Wed, Mar 21, 2018 at 02:45:44PM -0700, Yang Shi wrote:
> Marking vma as deleted sounds good. The problem for my current approach is
> the concurrent page fault may succeed if it access the not yet unmapped
> section. Marking deleted vma could tell page fault the vma is not valid
> anymore, then return SIGSEGV.
>
> > does not care; munmap will need to wait for the existing munmap operation
>
> Why mmap doesn't care? How about MAP_FIXED? It may fail unexpectedly, right?
The other thing about MAP_FIXED that we'll need to handle is unmapping
conflicts atomically. Say a program has a 200GB mapping and then
mmap(MAP_FIXED) another 200GB region on top of it. So I think page faults
are also going to have to wait for deleted vmas (then retry the fault)
rather than immediately raising SIGSEGV.
next prev parent reply other threads:[~2018-03-21 22:46 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 21:31 [RFC PATCH 0/8] Drop mmap_sem during unmapping large map Yang Shi
2018-03-20 21:31 ` [RFC PATCH 1/8] mm: mmap: unmap large mapping by section Yang Shi
2018-03-21 13:08 ` Michal Hocko
2018-03-21 16:31 ` Yang Shi
2018-03-21 17:29 ` Matthew Wilcox
2018-03-21 21:45 ` Yang Shi
2018-03-21 22:15 ` Matthew Wilcox
2018-03-21 22:40 ` Yang Shi
2018-03-21 22:46 ` Matthew Wilcox [this message]
2018-03-22 15:32 ` Laurent Dufour
2018-03-22 15:40 ` Matthew Wilcox
2018-03-22 15:54 ` Laurent Dufour
2018-03-22 16:05 ` Matthew Wilcox
2018-03-22 16:18 ` Laurent Dufour
2018-03-22 16:46 ` Yang Shi
2018-03-23 13:03 ` Laurent Dufour
2018-03-22 16:51 ` Matthew Wilcox
2018-03-22 16:49 ` Yang Shi
2018-03-22 17:34 ` Yang Shi
2018-03-22 18:48 ` Matthew Wilcox
2018-03-24 18:24 ` Jerome Glisse
2018-03-21 13:14 ` Michal Hocko
2018-03-21 16:50 ` Yang Shi
2018-03-21 17:16 ` Yang Shi
2018-03-21 21:23 ` Michal Hocko
2018-03-21 22:36 ` Yang Shi
2018-03-22 9:10 ` Michal Hocko
2018-03-22 16:06 ` Yang Shi
2018-03-22 16:12 ` Michal Hocko
2018-03-22 16:13 ` Matthew Wilcox
2018-03-22 16:28 ` Laurent Dufour
2018-03-22 16:36 ` David Laight
2018-03-20 21:31 ` [RFC PATCH 2/8] mm: mmap: pass atomic parameter to do_munmap() call sites Yang Shi
2018-03-20 21:31 ` [RFC PATCH 3/8] mm: mremap: pass atomic parameter to do_munmap() Yang Shi
2018-03-20 21:31 ` [RFC PATCH 4/8] mm: nommu: add " Yang Shi
2018-03-20 21:31 ` [RFC PATCH 5/8] ipc: shm: pass " Yang Shi
2018-03-20 21:31 ` [RFC PATCH 6/8] fs: proc/vmcore: " Yang Shi
2018-03-20 21:31 ` [RFC PATCH 7/8] x86: mpx: " Yang Shi
2018-03-20 22:35 ` Thomas Gleixner
2018-03-21 16:53 ` Yang Shi
2018-03-20 21:31 ` [RFC PATCH 8/8] x86: vma: " Yang Shi
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