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From: Michal Hocko <mhocko@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>,
	ldufour@linux.vnet.ibm.com, vbabka@suse.cz,
	akpm@linux-foundation.org, dave.hansen@intel.com,
	oleg@redhat.com, srikar@linux.vnet.ibm.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC v9 PATCH 2/4] mm: mmap: zap pages with read mmap_sem in munmap
Date: Wed, 12 Sep 2018 11:11:05 +0200	[thread overview]
Message-ID: <20180912091105.GB10951@dhcp22.suse.cz> (raw)
In-Reply-To: <20180912022921.GA20056@bombadil.infradead.org>

On Tue 11-09-18 19:29:21, Matthew Wilcox wrote:
> On Tue, Sep 11, 2018 at 04:35:03PM -0700, Yang Shi wrote:
[...]

I didn't get to read the patch yet.

> > And, Michal prefers have VM_HUGETLB and VM_PFNMAP handled separately for
> > safe and bisectable sake, which needs call the regular do_munmap().
> 
> That can be introduced and then taken out ... indeed, you can split this into
> many patches, starting with this:
> 
> +		if (tmp->vm_file)
> +			downgrade = false;
> 
> to only allow this optimisation for anonymous mappings at first.

or add a helper function to check for special cases and make the
downgrade behavior conditional on it.
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-09-12  9:11 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-11 20:58 [RFC v9 PATCH 0/4] mm: zap pages with read mmap_sem in munmap for large mapping Yang Shi
2018-09-11 20:58 ` [RFC v9 PATCH 1/4] mm: refactor do_munmap() to extract the common part Yang Shi
2018-09-11 20:58 ` [RFC v9 PATCH 2/4] mm: mmap: zap pages with read mmap_sem in munmap Yang Shi
2018-09-11 21:16   ` Matthew Wilcox
2018-09-11 23:35     ` Yang Shi
2018-09-12  2:29       ` Matthew Wilcox
2018-09-12  9:11         ` Michal Hocko [this message]
2018-09-12 17:15           ` Yang Shi
2018-09-11 20:58 ` [RFC v9 PATCH 3/4] mm: unmap VM_HUGETLB mappings with optimized path Yang Shi
2018-09-11 20:58 ` [RFC v9 PATCH 4/4] mm: unmap VM_PFNMAP " Yang Shi

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