Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd()
On Thu, Aug 15, 2019 at 03:40:21PM -0400, Jerome Glisse wrote:
> On Thu, Aug 15, 2019 at 12:23:44PM -0700, Ralph Campbell wrote:
> [...]
> >
> > I don't understand. The only use of "pfn" I see is in the "else"
> > clause above where it is set just before using it.
>
> Ok i managed to confuse myself with mpfn and probably with old
> version of the code. Sorry for reading too quickly. Can we move
> unsigned long pfn; into the else { branch so that there is no
> more confusion to its scope.
Looks better, I will update v3.
Thanks,
Pingfan
Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd()
On Thu, Aug 15, 2019 at 12:23:44PM -0700, Ralph Campbell wrote:
>
> On 8/15/19 10:19 AM, Jerome Glisse wrote:
> > On Wed, Aug 07, 2019 at 04:41:12PM +0800, Pingfan Liu wrote:
> > > Clean up useless 'pfn' variable.
> >
> > NAK there is a bug see below:
> >
> > >
> > > Signed-off-by: Pingfan Liu
> > > Cc: "Jérôme Glisse"
> > > Cc: Andrew Morton
> > > Cc: Mel Gorman
> > > Cc: Jan Kara
> > > Cc: "Kirill A. Shutemov"
> > > Cc: Michal Hocko
> > > Cc: Mike Kravetz
> > > Cc: Andrea Arcangeli
> > > Cc: Matthew Wilcox
> > > To: linux...@kvack.org
> > > Cc: linux-kernel@vger.kernel.org
> > > ---
> > > mm/migrate.c | 9 +++--
> > > 1 file changed, 3 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/mm/migrate.c b/mm/migrate.c
> > > index 8992741..d483a55 100644
> > > --- a/mm/migrate.c
> > > +++ b/mm/migrate.c
> > > @@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> > > pte_t pte;
> > > pte = *ptep;
> > > - pfn = pte_pfn(pte);
> > > if (pte_none(pte)) {
> > > mpfn = MIGRATE_PFN_MIGRATE;
> > > migrate->cpages++;
> > > - pfn = 0;
> > > goto next;
> > > }
> > > if (!pte_present(pte)) {
> > > - mpfn = pfn = 0;
> > > + mpfn = 0;
> > > /*
> > >* Only care about unaddressable device page
> > > special
> > > @@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> > > if (is_write_device_private_entry(entry))
> > > mpfn |= MIGRATE_PFN_WRITE;
> > > } else {
> > > + pfn = pte_pfn(pte);
> > > if (is_zero_pfn(pfn)) {
> > > mpfn = MIGRATE_PFN_MIGRATE;
> > > migrate->cpages++;
> > > - pfn = 0;
> > > goto next;
> > > }
> > > page = vm_normal_page(migrate->vma, addr, pte);
> > > @@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> > > /* FIXME support THP */
> > > if (!page || !page->mapping || PageTransCompound(page))
> > > {
> > > - mpfn = pfn = 0;
> > > + mpfn = 0;
> > > goto next;
> > > }
> > > - pfn = page_to_pfn(page);
> >
> > You can not remove that one ! Otherwise it will break the device
> > private case.
> >
>
> I don't understand. The only use of "pfn" I see is in the "else"
> clause above where it is set just before using it.
Ok i managed to confuse myself with mpfn and probably with old
version of the code. Sorry for reading too quickly. Can we move
unsigned long pfn; into the else { branch so that there is no
more confusion to its scope.
Cheers,
Jérôme
Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd()
On 8/15/19 10:19 AM, Jerome Glisse wrote:
On Wed, Aug 07, 2019 at 04:41:12PM +0800, Pingfan Liu wrote:
Clean up useless 'pfn' variable.
NAK there is a bug see below:
Signed-off-by: Pingfan Liu
Cc: "Jérôme Glisse"
Cc: Andrew Morton
Cc: Mel Gorman
Cc: Jan Kara
Cc: "Kirill A. Shutemov"
Cc: Michal Hocko
Cc: Mike Kravetz
Cc: Andrea Arcangeli
Cc: Matthew Wilcox
To: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/migrate.c | 9 +++--
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 8992741..d483a55 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
pte_t pte;
pte = *ptep;
- pfn = pte_pfn(pte);
if (pte_none(pte)) {
mpfn = MIGRATE_PFN_MIGRATE;
migrate->cpages++;
- pfn = 0;
goto next;
}
if (!pte_present(pte)) {
- mpfn = pfn = 0;
+ mpfn = 0;
/*
* Only care about unaddressable device page special
@@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
if (is_write_device_private_entry(entry))
mpfn |= MIGRATE_PFN_WRITE;
} else {
+ pfn = pte_pfn(pte);
if (is_zero_pfn(pfn)) {
mpfn = MIGRATE_PFN_MIGRATE;
migrate->cpages++;
- pfn = 0;
goto next;
}
page = vm_normal_page(migrate->vma, addr, pte);
@@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
/* FIXME support THP */
if (!page || !page->mapping || PageTransCompound(page)) {
- mpfn = pfn = 0;
+ mpfn = 0;
goto next;
}
- pfn = page_to_pfn(page);
You can not remove that one ! Otherwise it will break the device
private case.
I don't understand. The only use of "pfn" I see is in the "else"
clause above where it is set just before using it.
Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd()
On Wed, Aug 07, 2019 at 04:41:12PM +0800, Pingfan Liu wrote:
> Clean up useless 'pfn' variable.
NAK there is a bug see below:
>
> Signed-off-by: Pingfan Liu
> Cc: "Jérôme Glisse"
> Cc: Andrew Morton
> Cc: Mel Gorman
> Cc: Jan Kara
> Cc: "Kirill A. Shutemov"
> Cc: Michal Hocko
> Cc: Mike Kravetz
> Cc: Andrea Arcangeli
> Cc: Matthew Wilcox
> To: linux...@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
> mm/migrate.c | 9 +++--
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 8992741..d483a55 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> pte_t pte;
>
> pte = *ptep;
> - pfn = pte_pfn(pte);
>
> if (pte_none(pte)) {
> mpfn = MIGRATE_PFN_MIGRATE;
> migrate->cpages++;
> - pfn = 0;
> goto next;
> }
>
> if (!pte_present(pte)) {
> - mpfn = pfn = 0;
> + mpfn = 0;
>
> /*
>* Only care about unaddressable device page special
> @@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> if (is_write_device_private_entry(entry))
> mpfn |= MIGRATE_PFN_WRITE;
> } else {
> + pfn = pte_pfn(pte);
> if (is_zero_pfn(pfn)) {
> mpfn = MIGRATE_PFN_MIGRATE;
> migrate->cpages++;
> - pfn = 0;
> goto next;
> }
> page = vm_normal_page(migrate->vma, addr, pte);
> @@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>
> /* FIXME support THP */
> if (!page || !page->mapping || PageTransCompound(page)) {
> - mpfn = pfn = 0;
> + mpfn = 0;
> goto next;
> }
> - pfn = page_to_pfn(page);
You can not remove that one ! Otherwise it will break the device
private case.
Re: [PATCHv2] mm/migrate: clean up useless code in migrate_vma_collect_pmd()
On 8/7/19 1:41 AM, Pingfan Liu wrote:
Clean up useless 'pfn' variable.
Signed-off-by: Pingfan Liu
Cc: "Jérôme Glisse"
Cc: Andrew Morton
Cc: Mel Gorman
Cc: Jan Kara
Cc: "Kirill A. Shutemov"
Cc: Michal Hocko
Cc: Mike Kravetz
Cc: Andrea Arcangeli
Cc: Matthew Wilcox
To: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/migrate.c | 9 +++--
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 8992741..d483a55 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2225,17 +2225,15 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
pte_t pte;
pte = *ptep;
- pfn = pte_pfn(pte);
if (pte_none(pte)) {
mpfn = MIGRATE_PFN_MIGRATE;
migrate->cpages++;
- pfn = 0;
goto next;
}
if (!pte_present(pte)) {
- mpfn = pfn = 0;
+ mpfn = 0;
/*
* Only care about unaddressable device page special
@@ -2252,10 +2250,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
if (is_write_device_private_entry(entry))
mpfn |= MIGRATE_PFN_WRITE;
} else {
+ pfn = pte_pfn(pte);
if (is_zero_pfn(pfn)) {
mpfn = MIGRATE_PFN_MIGRATE;
migrate->cpages++;
- pfn = 0;
goto next;
}
page = vm_normal_page(migrate->vma, addr, pte);
@@ -2265,10 +2263,9 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
/* FIXME support THP */
if (!page || !page->mapping || PageTransCompound(page)) {
- mpfn = pfn = 0;
+ mpfn = 0;
goto next;
}
- pfn = page_to_pfn(page);
/*
* By getting a reference on the page we pin it and that blocks
Thanks, I was planning to do this too.
Reviewed-by: Ralph Campbell
