From: Rik van Riel <riel@surriel.com>
To: Vlastimil Babka <vbabka@suse.cz>, hughd@google.com
Cc: xuyu@linux.alibaba.com, akpm@linux-foundation.org,
mgorman@suse.de, aarcange@redhat.com, willy@infradead.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com,
linux-mm@kvack.org, mhocko@suse.com
Subject: Re: [PATCH 3/3] mm,thp,shmem: make khugepaged obey tmpfs mount flags
Date: Thu, 26 Nov 2020 13:14:55 -0500 [thread overview]
Message-ID: <8f2428a049f2c29f092782699bcb3af76bf72b6a.camel@surriel.com> (raw)
In-Reply-To: <eda496c8-e248-c8fe-e7bd-f7e71d20e499@suse.cz>
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On Thu, 2020-11-26 at 18:18 +0100, Vlastimil Babka wrote:
> On 11/24/20 8:49 PM, Rik van Riel wrote:
> > Currently if thp enabled=[madvise], mounting a tmpfs filesystem
> > with huge=always and mmapping files from that tmpfs does not
> > result in khugepaged collapsing those mappings, despite the
> > mount flag indicating that it should.
> >
> > Fix that by breaking up the blocks of tests in hugepage_vma_check
> > a little bit, and testing things in the correct order.
> >
> > Signed-off-by: Rik van Riel <riel@surriel.com>
> > Fixes: c2231020ea7b ("mm: thp: register mm for khugepaged when
> > merging vma for shmem")
>
> Looks ok. But, it we have sysfs thp enabled=never, and shmem mount
> explicitly
> thp enabled, then shmem mount overrides the global sysfs setting and
> thp's will
> be allocated there, right? However, khugepaged_enabled() will be
> false and thus
> khugepaged won't run at all? So a similar situation than what you're
> fixing here.
Indeed, that is somewhat similar. Whether or not shmem
allocations attempt huge pages is controlled by both
the file /sys/kernel/mm/transparent_hugepage/shmem_enabled
and mount options.
This patch makes khugepaged treat the mount options
and/or
sysfs flag as enabling collapsing of huge pages in case
enabled = [always] for regular THPs.
Should I send another patch on top
of this that causes
khugepaged to be enabled when regular THPs are disabled,
but shmem THPs are enabled in any way?
--
All Rights Reversed.
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next prev parent reply other threads:[~2020-11-26 18:15 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 19:49 [PATCH v6 0/3] mm,thp,shm: limit shmem THP alloc gfp_mask Rik van Riel
2020-11-24 19:49 ` [PATCH 1/3] mm,thp,shmem: " Rik van Riel
2020-11-26 16:56 ` Vlastimil Babka
2020-11-27 8:15 ` Michal Hocko
2020-11-24 19:49 ` [PATCH 2/3] mm,thp,shm: limit gfp mask to no more than specified Rik van Riel
2020-11-26 13:40 ` Michal Hocko
2020-11-26 18:04 ` Rik van Riel
2020-11-27 7:52 ` Michal Hocko
2020-11-27 19:03 ` Rik van Riel
2020-11-30 10:00 ` Michal Hocko
2020-11-30 14:40 ` Rik van Riel
2020-11-24 19:49 ` [PATCH 3/3] mm,thp,shmem: make khugepaged obey tmpfs mount flags Rik van Riel
2020-11-26 17:18 ` Vlastimil Babka
2020-11-26 18:14 ` Rik van Riel [this message]
2020-11-26 19:42 ` Vlastimil Babka
2020-11-26 20:14 ` Rik van Riel
2020-12-14 21:16 ` [PATCH v6 0/3] mm,thp,shm: limit shmem THP alloc gfp_mask Hugh Dickins
2020-12-14 22:20 ` Andrew Morton
2020-12-14 22:52 ` Vlastimil Babka
2021-02-24 8:41 ` Hugh Dickins
2021-02-24 14:46 ` Rik van Riel
2021-02-24 16:55 ` Hugh Dickins
2021-02-24 17:10 ` [PATCH 4/3] mm,shmem,thp: limit shmem THP allocations to requested zones Rik van Riel
2021-02-26 12:34 ` Vlastimil Babka
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