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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Hugh Dickins <hughd@google.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org
Subject: Re: [PATCH next] powerpc/mm: fix _PAGE_SWP_SOFT_DIRTY breaking swapoff
Date: Sun, 10 Jan 2016 17:07:40 +0300	[thread overview]
Message-ID: <20160110140740.GB4306@uranus> (raw)
In-Reply-To: <alpine.LSU.2.11.1601091651130.9808@eggly.anvils>

On Sat, Jan 09, 2016 at 04:54:59PM -0800, Hugh Dickins wrote:
> Swapoff after swapping hangs on the G5, when CONFIG_CHECKPOINT_RESTORE=y
> but CONFIG_MEM_SOFT_DIRTY is not set.  That's because the non-zero
> _PAGE_SWP_SOFT_DIRTY bit, added by CONFIG_HAVE_ARCH_SOFT_DIRTY=y, is not
> discounted when CONFIG_MEM_SOFT_DIRTY is not set: so swap ptes cannot be
> recognized.
> 
> (I suspect that the peculiar dependence of HAVE_ARCH_SOFT_DIRTY on
> CHECKPOINT_RESTORE in arch/powerpc/Kconfig comes from an incomplete
> attempt to solve this problem.)
> 
> It's true that the relationship between CONFIG_HAVE_ARCH_SOFT_DIRTY and
> and CONFIG_MEM_SOFT_DIRTY is too confusing, and it's true that swapoff
> should be made more robust; but nevertheless, fix up the powerpc ifdefs
> as x86_64 and s390 (which met the same problem) have them, defining the
> bits as 0 if CONFIG_MEM_SOFT_DIRTY is not set.
> 
> Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>

Thank you, Hugh!

WARNING: multiple messages have this Message-ID (diff)
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Hugh Dickins <hughd@google.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org
Subject: Re: [PATCH next] powerpc/mm: fix _PAGE_SWP_SOFT_DIRTY breaking swapoff
Date: Sun, 10 Jan 2016 17:07:40 +0300	[thread overview]
Message-ID: <20160110140740.GB4306@uranus> (raw)
In-Reply-To: <alpine.LSU.2.11.1601091651130.9808@eggly.anvils>

On Sat, Jan 09, 2016 at 04:54:59PM -0800, Hugh Dickins wrote:
> Swapoff after swapping hangs on the G5, when CONFIG_CHECKPOINT_RESTORE=y
> but CONFIG_MEM_SOFT_DIRTY is not set.  That's because the non-zero
> _PAGE_SWP_SOFT_DIRTY bit, added by CONFIG_HAVE_ARCH_SOFT_DIRTY=y, is not
> discounted when CONFIG_MEM_SOFT_DIRTY is not set: so swap ptes cannot be
> recognized.
> 
> (I suspect that the peculiar dependence of HAVE_ARCH_SOFT_DIRTY on
> CHECKPOINT_RESTORE in arch/powerpc/Kconfig comes from an incomplete
> attempt to solve this problem.)
> 
> It's true that the relationship between CONFIG_HAVE_ARCH_SOFT_DIRTY and
> and CONFIG_MEM_SOFT_DIRTY is too confusing, and it's true that swapoff
> should be made more robust; but nevertheless, fix up the powerpc ifdefs
> as x86_64 and s390 (which met the same problem) have them, defining the
> bits as 0 if CONFIG_MEM_SOFT_DIRTY is not set.
> 
> Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>

Thank you, Hugh!

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  parent reply	other threads:[~2016-01-10 14:07 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-10  0:54 [PATCH next] powerpc/mm: fix _PAGE_SWP_SOFT_DIRTY breaking swapoff Hugh Dickins
2016-01-10  0:54 ` Hugh Dickins
2016-01-10  0:59 ` [PATCH next] mm: make swapoff more robust against soft dirty Hugh Dickins
2016-01-10  0:59   ` Hugh Dickins
2016-01-10 14:09   ` Cyrill Gorcunov
2016-01-10 14:09     ` Cyrill Gorcunov
2016-01-11  5:39   ` Aneesh Kumar K.V
2016-01-11  5:39     ` Aneesh Kumar K.V
2016-01-10 14:07 ` Cyrill Gorcunov [this message]
2016-01-10 14:07   ` [PATCH next] powerpc/mm: fix _PAGE_SWP_SOFT_DIRTY breaking swapoff Cyrill Gorcunov
2016-01-11  5:43 ` Aneesh Kumar K.V
2016-01-11  5:43   ` Aneesh Kumar K.V
2016-01-11  6:05   ` Hugh Dickins
2016-01-11  6:05     ` Hugh Dickins
2016-01-11  6:31     ` Aneesh Kumar K.V
2016-01-11  6:31       ` Aneesh Kumar K.V
2016-01-11  7:33       ` Hugh Dickins
2016-01-11  7:33         ` Hugh Dickins
2016-01-11 16:04 ` Laurent Dufour
2016-01-11 16:04   ` Laurent Dufour
2016-01-12 12:32 ` [next] " Michael Ellerman
2016-01-12 12:32   ` Michael Ellerman

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