From: Hugh Dickins <hughd@google.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Ning Qu <quning@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 03/24] mm: use __SetPageSwapBacked and don't ClearPageSwapBacked
Date: Sun, 22 Mar 2015 20:01:13 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.11.1503221944530.4290@eggly.anvils> (raw)
In-Reply-To: <20150225105315.GK23372@suse.de>
On Wed, 25 Feb 2015, Mel Gorman wrote:
> On Fri, Feb 20, 2015 at 07:56:15PM -0800, Hugh Dickins wrote:
> > Commit 07a427884348 ("mm: shmem: avoid atomic operation during
> > shmem_getpage_gfp") rightly replaced one instance of SetPageSwapBacked
> > by __SetPageSwapBacked, pointing out that the newly allocated page is
> > not yet visible to other users (except speculative get_page_unless_zero-
> > ers, who may not update page flags before their further checks).
> >
> > That was part of a series in which Mel was focused on tmpfs profiles:
> > but almost all SetPageSwapBacked uses can be so optimized, with the
> > same justification. And remove the ClearPageSwapBacked from
> > read_swap_cache_async()'s and zswap_get_swap_cache_page()'s error
> > paths: it's not an error to free a page with PG_swapbacked set.
> >
> > (There's probably scope for further __SetPageFlags in other places,
> > but SwapBacked is the one I'm interested in at the moment.)
> >
> > Signed-off-by: Hugh Dickins <hughd@google.com>
> > ---
> > mm/migrate.c | 6 +++---
> > mm/rmap.c | 2 +-
> > mm/shmem.c | 4 ++--
> > mm/swap_state.c | 3 +--
> > mm/zswap.c | 3 +--
> > 5 files changed, 8 insertions(+), 10 deletions(-)
> >
> > <SNIP>
> > --- thpfs.orig/mm/shmem.c 2015-02-08 18:54:22.000000000 -0800
> > +++ thpfs/mm/shmem.c 2015-02-20 19:33:35.676074594 -0800
> > @@ -987,8 +987,8 @@ static int shmem_replace_page(struct pag
> > flush_dcache_page(newpage);
> >
> > __set_page_locked(newpage);
> > + __SetPageSwapBacked(newpage);
> > SetPageUptodate(newpage);
> > - SetPageSwapBacked(newpage);
> > set_page_private(newpage, swap_index);
> > SetPageSwapCache(newpage);
> >
>
> It's clear why you did this but ...
>
> > @@ -1177,8 +1177,8 @@ repeat:
> > goto decused;
> > }
> >
> > - __SetPageSwapBacked(page);
> > __set_page_locked(page);
> > + __SetPageSwapBacked(page);
> > if (sgp == SGP_WRITE)
> > __SetPageReferenced(page);
> >
>
> It's less clear why this was necessary.
I don't think the reordering was necessary in either case
(though perhaps the first hunk makes a subsequent patch smaller).
I just get irritated by seeing the same lines of code permuted
in different ways for no reason, and thought I'd tidy them up
to establish one familiar sequence, that's all.
> I don't think it causes any problems though so
>
> Reviewed-by: Mel Gorman <mgorman@suse.de>
Thanks!
Hugh
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next prev parent reply other threads:[~2015-03-23 3:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-21 3:49 [PATCH 00/24] huge tmpfs: an alternative approach to THPageCache Hugh Dickins
2015-02-21 3:51 ` [PATCH 01/24] mm: update_lru_size warn and reset bad lru_size Hugh Dickins
2015-02-23 9:30 ` Kirill A. Shutemov
2015-03-23 2:44 ` Hugh Dickins
2015-02-21 3:54 ` [PATCH 02/24] mm: update_lru_size do the __mod_zone_page_state Hugh Dickins
2015-02-21 3:56 ` [PATCH 03/24] mm: use __SetPageSwapBacked and don't ClearPageSwapBacked Hugh Dickins
2015-02-25 10:53 ` Mel Gorman
2015-03-23 3:01 ` Hugh Dickins [this message]
2015-02-21 3:58 ` [PATCH 04/24] mm: make page migration's newpage handling more robust Hugh Dickins
2015-02-21 4:00 ` [PATCH 05/24] tmpfs: preliminary minor tidyups Hugh Dickins
2015-02-21 4:01 ` [PATCH 06/24] huge tmpfs: prepare counts in meminfo, vmstat and SysRq-m Hugh Dickins
2015-02-21 4:03 ` [PATCH 07/24] huge tmpfs: include shmem freeholes in available memory counts Hugh Dickins
2015-02-21 4:05 ` [PATCH 08/24] huge tmpfs: prepare huge=N mount option and /proc/sys/vm/shmem_huge Hugh Dickins
2015-02-21 4:06 ` [PATCH 09/24] huge tmpfs: try to allocate huge pages, split into a team Hugh Dickins
2015-02-21 4:07 ` [PATCH 10/24] huge tmpfs: avoid team pages in a few places Hugh Dickins
2015-02-21 4:09 ` [PATCH 11/24] huge tmpfs: shrinker to migrate and free underused holes Hugh Dickins
2015-03-19 16:56 ` Konstantin Khlebnikov
2015-03-23 4:40 ` Hugh Dickins
2015-03-23 12:50 ` Kirill A. Shutemov
2015-03-23 13:50 ` Kirill A. Shutemov
2015-03-24 12:57 ` Kirill A. Shutemov
2015-03-25 0:41 ` Hugh Dickins
2015-02-21 4:11 ` [PATCH 12/24] huge tmpfs: get_unmapped_area align and fault supply huge page Hugh Dickins
2015-02-21 4:12 ` [PATCH 13/24] huge tmpfs: extend get_user_pages_fast to shmem pmd Hugh Dickins
2015-02-21 4:13 ` [PATCH 14/24] huge tmpfs: extend vma_adjust_trans_huge " Hugh Dickins
2015-02-21 4:15 ` [PATCH 15/24] huge tmpfs: rework page_referenced_one and try_to_unmap_one Hugh Dickins
2015-02-21 4:16 ` [PATCH 16/24] huge tmpfs: fix problems from premature exposure of pagetable Hugh Dickins
2015-07-01 10:53 ` Kirill A. Shutemov
2015-02-21 4:18 ` [PATCH 17/24] huge tmpfs: map shmem by huge page pmd or by page team ptes Hugh Dickins
2015-02-21 4:20 ` [PATCH 18/24] huge tmpfs: mmap_sem is unlocked when truncation splits huge pmd Hugh Dickins
2015-02-21 4:22 ` [PATCH 19/24] huge tmpfs: disband split huge pmds on race or memory failure Hugh Dickins
2015-02-21 4:23 ` [PATCH 20/24] huge tmpfs: use Unevictable lru with variable hpage_nr_pages() Hugh Dickins
2015-02-21 4:25 ` [PATCH 21/24] huge tmpfs: fix Mlocked meminfo, tracking huge and unhuge mlocks Hugh Dickins
2015-02-21 4:27 ` [PATCH 22/24] huge tmpfs: fix Mapped meminfo, tracking huge and unhuge mappings Hugh Dickins
2015-02-21 4:29 ` [PATCH 23/24] kvm: plumb return of hva when resolving page fault Hugh Dickins
2015-02-21 4:31 ` [PATCH 24/24] kvm: teach kvm to map page teams as huge pages Hugh Dickins
2015-02-23 13:48 ` [PATCH 00/24] huge tmpfs: an alternative approach to THPageCache Kirill A. Shutemov
2015-03-23 2:25 ` Hugh Dickins
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