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From: Nicholas Piggin <npiggin@gmail.com>
To: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Bob Peterson <rpeterso@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	swhiteho@redhat.com, luto@kernel.org, agruenba@redhat.com,
	peterz@infradead.org, linux-mm@kvack.org,
	Mel Gorman <mgorman@techsingularity.net>
Subject: Re: [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked
Date: Sun, 25 Dec 2016 11:00:49 +1000	[thread overview]
Message-ID: <20161225110049.09dc48fc@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <alpine.LSU.2.11.1612221130520.4215@eggly.anvils>

On Thu, 22 Dec 2016 11:55:28 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:

> On Thu, 22 Dec 2016, Nicholas Piggin wrote:
> 
> I agree with every word of that changelog ;)
> 
> And I'll stamp this with
> Acked-by: Hugh Dickins <hughd@google.com>

Thanks Hugh.
 
> The thing that Peter remembers I commented on (which 0day caught too),
> was to remove PG_swapcache from PAGE_FLAGS_CHECK_AT_FREE: you've done
> that now, so this is good.  (Note in passing: wouldn't it be good to
> add PG_waiters to PAGE_FLAGS_CHECK_AT_FREE in the 2/2?)
> 
> Though I did yesterday notice a few more problematic uses of
> PG_swapcache, which you'll probably need to refine to exclude
> other uses of PG_owner_priv_1; though no great hurry for those,
> so not necessarily in this same patch.  Do your own grep, but
> 
> fs/proc/page.c derives its KPF_SWAPCACHE from PG_swapcache,
> needs refining.
> 
> kernel/kexec_core.c says VMCOREINFO_NUMBER(PG_swapcache):
> I haven't looked into what that's about, it will probably just
> have to be commented as now including other uses of the same bit.
> 
> mm/memory-failure.c has an error_states[] table that involves
> testing PG_swapcache as "sc", but looks as if it can be changed
> to factor in "swapbacked" too.

I've added the swapbacked check to mm/memory-failure.c, the others look
like they're just dealing with bit number, so not much to do about it
really. I also just made the migration case more explicit, seeing as the
others are.

Hopefully that doesn't negate your ack because I'm adding that too.

Thanks,
Nick

WARNING: multiple messages have this Message-ID (diff)
From: Nicholas Piggin <npiggin@gmail.com>
To: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Bob Peterson <rpeterso@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	swhiteho@redhat.com, luto@kernel.org, agruenba@redhat.com,
	peterz@infradead.org, linux-mm@kvack.org,
	Mel Gorman <mgorman@techsingularity.net>
Subject: Re: [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked
Date: Sun, 25 Dec 2016 11:00:49 +1000	[thread overview]
Message-ID: <20161225110049.09dc48fc@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <alpine.LSU.2.11.1612221130520.4215@eggly.anvils>

On Thu, 22 Dec 2016 11:55:28 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:

> On Thu, 22 Dec 2016, Nicholas Piggin wrote:
> 
> I agree with every word of that changelog ;)
> 
> And I'll stamp this with
> Acked-by: Hugh Dickins <hughd@google.com>

Thanks Hugh.
 
> The thing that Peter remembers I commented on (which 0day caught too),
> was to remove PG_swapcache from PAGE_FLAGS_CHECK_AT_FREE: you've done
> that now, so this is good.  (Note in passing: wouldn't it be good to
> add PG_waiters to PAGE_FLAGS_CHECK_AT_FREE in the 2/2?)
> 
> Though I did yesterday notice a few more problematic uses of
> PG_swapcache, which you'll probably need to refine to exclude
> other uses of PG_owner_priv_1; though no great hurry for those,
> so not necessarily in this same patch.  Do your own grep, but
> 
> fs/proc/page.c derives its KPF_SWAPCACHE from PG_swapcache,
> needs refining.
> 
> kernel/kexec_core.c says VMCOREINFO_NUMBER(PG_swapcache):
> I haven't looked into what that's about, it will probably just
> have to be commented as now including other uses of the same bit.
> 
> mm/memory-failure.c has an error_states[] table that involves
> testing PG_swapcache as "sc", but looks as if it can be changed
> to factor in "swapbacked" too.

I've added the swapbacked check to mm/memory-failure.c, the others look
like they're just dealing with bit number, so not much to do about it
really. I also just made the migration case more explicit, seeing as the
others are.

Hopefully that doesn't negate your ack because I'm adding that too.

Thanks,
Nick

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  reply	other threads:[~2016-12-25  1:01 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-21 15:19 [PATCH 0/2] respin of PageWaiters patch Nicholas Piggin
2016-12-21 15:19 ` Nicholas Piggin
2016-12-21 15:19 ` [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Nicholas Piggin
2016-12-21 15:19   ` Nicholas Piggin
2016-12-22 19:55   ` Hugh Dickins
2016-12-22 19:55     ` Hugh Dickins
2016-12-25  1:00     ` Nicholas Piggin [this message]
2016-12-25  1:00       ` Nicholas Piggin
2016-12-24 19:51   ` Linus Torvalds
2016-12-24 19:51     ` Linus Torvalds
2016-12-21 15:19 ` [PATCH 2/2] mm: add PageWaiters bit to indicate waitqueue should be checked Nicholas Piggin
2016-12-21 15:19   ` Nicholas Piggin
2016-12-21 17:30 ` [PATCH 0/2] respin of PageWaiters patch Linus Torvalds
2016-12-21 17:30   ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2016-12-25  3:00 [PATCH 0/2] PageWaiters again Nicholas Piggin
2016-12-25  3:00 ` [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Nicholas Piggin
2016-12-25  3:00   ` Nicholas Piggin
2016-12-25  5:13   ` Hugh Dickins
2016-12-25  5:13     ` Hugh Dickins
2016-11-02  7:03 [RFC][PATCH 0/2] optimise unlock_page / end_page_writeback Nicholas Piggin
2016-11-02  7:03 ` [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Nicholas Piggin
2016-11-04  2:20   ` Hugh Dickins
2016-11-11  0:58     ` Nicholas Piggin

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