From: Matthew Wilcox <willy@infradead.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, mhocko@kernel.org, mhocko@suse.com,
rientjes@google.com, hannes@cmpxchg.org, guro@fb.com,
riel@surriel.com, minchan@kernel.org, kirill@shutemov.name,
aarcange@redhat.com, christian@brauner.io, hch@infradead.org,
oleg@redhat.com, david@redhat.com, jannh@google.com,
shakeelb@google.com, luto@kernel.org,
christian.brauner@ubuntu.com, fweimer@redhat.com,
jengelh@inai.de, timmurray@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH v3 1/2] mm: protect free_pgtables with mmap_lock write lock in exit_mmap
Date: Wed, 8 Dec 2021 15:01:24 +0000 [thread overview]
Message-ID: <YbDIxA92ln+RTbUK@casper.infradead.org> (raw)
In-Reply-To: <CAJuCfpG-CU4AywZGDfMRiEtxMWkL4KMJ-xD1eM15C_z5eYdCJA@mail.gmail.com>
On Tue, Dec 07, 2021 at 03:08:19PM -0800, Suren Baghdasaryan wrote:
> > > /**
> > > * @close: Called when the VMA is being removed from the MM.
> > > * Context: Caller holds mmap_lock.
>
> BTW, is the caller always required to hold mmap_lock for write or it
> *might* hold it?
__do_munmap() might hold it for read, thanks to:
if (downgrade)
mmap_write_downgrade(mm);
Should probably say:
* Context: User context. May sleep. Caller holds mmap_lock.
I don't think we should burden the implementor of the vm_ops with the
knowledge that the VM chooses to not hold the mmap_lock under certain
circumstances when it doesn't matter whether it's holding the mmap_lock
or not.
next prev parent reply other threads:[~2021-12-08 15:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 21:50 [PATCH v3 1/2] mm: protect free_pgtables with mmap_lock write lock in exit_mmap Suren Baghdasaryan
2021-12-07 21:50 ` [PATCH v3 2/2] mm/oom_kill: allow process_mrelease to run under mmap_lock protection Suren Baghdasaryan
2021-12-07 22:07 ` [PATCH v3 1/2] mm: protect free_pgtables with mmap_lock write lock in exit_mmap Matthew Wilcox
2021-12-07 22:47 ` Suren Baghdasaryan
2021-12-07 23:08 ` Suren Baghdasaryan
2021-12-08 8:56 ` Michal Hocko
2021-12-08 15:01 ` Matthew Wilcox [this message]
2021-12-08 15:51 ` Michal Hocko
2021-12-08 16:05 ` Matthew Wilcox
2021-12-08 16:50 ` Suren Baghdasaryan
2021-12-08 19:13 ` Suren Baghdasaryan
2021-12-08 19:22 ` Matthew Wilcox
2021-12-08 21:24 ` Suren Baghdasaryan
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