Re: [PATCH] powerpc: thp: Fix crash on mremap
On Tue, Jan 28, 2014 at 05:47:03PM +0530, Aneesh Kumar K.V wrote:
> This patch fix the below crash
>
> NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
> LR [c00439ac] .hash_page+0x18c/0x5e0
> ...
> Call Trace:
> [c00736103c40] [1b00] 0x1b00(unreliable)
> [437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
> [437908.479699] [c00736103e30] [c000924c] .do_hash_page+0x4c/0x58
>
> On ppc64 we use the pgtable for storing the hpte slot information and
> store address to the pgtable at a constant offset (PTRS_PER_PMD) from
> pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
> the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
> from new pmd.
>
> We also want to move the withdraw and deposit before the set_pmd so
> that, when page fault find the pmd as trans huge we can be sure that
> pgtable can be located at the offset.
>
> variant of upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f
> for 3.11 stable series
>
Since both you and Benjamin Herrenschmidt claim this is good for stable, I
am queuing this variant for the 3.11 kernel. Thanks a lot!
Cheers,
--
Luis
> Signed-off-by: Aneesh Kumar K.V
> ---
> arch/Kconfig | 3 +++
> arch/powerpc/platforms/Kconfig.cputype | 1 +
> mm/huge_memory.c | 12
> 3 files changed, 16 insertions(+)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 1feb169274fe..c5863b35d054 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -368,6 +368,9 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
> config HAVE_ARCH_SOFT_DIRTY
> bool
>
> +config ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
> + bool
> +
> config HAVE_MOD_ARCH_SPECIFIC
> bool
> help
> diff --git a/arch/powerpc/platforms/Kconfig.cputype
> b/arch/powerpc/platforms/Kconfig.cputype
> index 47d9a03dd415..d11a34be018d 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -71,6 +71,7 @@ config PPC_BOOK3S_64
> select PPC_FPU
> select PPC_HAVE_PMU_SUPPORT
> select SYS_SUPPORTS_HUGETLBFS
> + select ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
> select HAVE_ARCH_TRANSPARENT_HUGEPAGE if PPC_64K_PAGES
>
> config PPC_BOOK3E_64
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 12acb0ba7991..beaa7cc9de75 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1461,8 +1461,20 @@ int move_huge_pmd(struct vm_area_struct *vma, struct
> vm_area_struct *new_vma,
>
> ret = __pmd_trans_huge_lock(old_pmd, vma);
> if (ret == 1) {
> +#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
> + pgtable_t pgtable;
> +#endif
> pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
> VM_BUG_ON(!pmd_none(*new_pmd));
> +#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
> + /*
> + * Archs like ppc64 use pgtable to store per pmd
> + * specific information. So when we switch the pmd,
> + * we should also withdraw and deposit the pgtable
> + */
> + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
> + pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> +#endif
> set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
> spin_unlock(&mm->page_table_lock);
> }
> --
> 1.8.5.3
>
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[PATCH] powerpc: thp: Fix crash on mremap
This patch fix the below crash
NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
LR [c00439ac] .hash_page+0x18c/0x5e0
...
Call Trace:
[c00736103c40] [1b00] 0x1b00(unreliable)
[437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
[437908.479699] [c00736103e30] [c000924c] .do_hash_page+0x4c/0x58
On ppc64 we use the pgtable for storing the hpte slot information and
store address to the pgtable at a constant offset (PTRS_PER_PMD) from
pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
from new pmd.
We also want to move the withdraw and deposit before the set_pmd so
that, when page fault find the pmd as trans huge we can be sure that
pgtable can be located at the offset.
variant of upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f
for 3.12 stable series
Signed-off-by: Aneesh Kumar K.V
---
arch/Kconfig | 3 +++
arch/powerpc/platforms/Kconfig.cputype | 1 +
mm/huge_memory.c | 12
3 files changed, 16 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index af2cc6eabcc7..bca9e7a18bd2 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -365,6 +365,9 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
config HAVE_ARCH_SOFT_DIRTY
bool
+config ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ bool
+
config HAVE_MOD_ARCH_SPECIFIC
bool
help
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index 6704e2e20e6b..0225011231ea 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -71,6 +71,7 @@ config PPC_BOOK3S_64
select PPC_FPU
select PPC_HAVE_PMU_SUPPORT
select SYS_SUPPORTS_HUGETLBFS
+ select ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if PPC_64K_PAGES
config PPC_BOOK3E_64
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 292a266e0d42..89b7a647f1cb 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1474,8 +1474,20 @@ int move_huge_pmd(struct vm_area_struct *vma, struct
vm_area_struct *new_vma,
ret = __pmd_trans_huge_lock(old_pmd, vma);
if (ret == 1) {
+#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ pgtable_t pgtable;
+#endif
pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
+#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ /*
+* Archs like ppc64 use pgtable to store per pmd
+* specific information. So when we switch the pmd,
+* we should also withdraw and deposit the pgtable
+*/
+ pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+ pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+#endif
set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
spin_unlock(&mm->page_table_lock);
}
--
1.8.5.3
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[PATCH] powerpc: thp: Fix crash on mremap
This patch fix the below crash
NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
LR [c00439ac] .hash_page+0x18c/0x5e0
...
Call Trace:
[c00736103c40] [1b00] 0x1b00(unreliable)
[437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
[437908.479699] [c00736103e30] [c000924c] .do_hash_page+0x4c/0x58
On ppc64 we use the pgtable for storing the hpte slot information and
store address to the pgtable at a constant offset (PTRS_PER_PMD) from
pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
from new pmd.
We also want to move the withdraw and deposit before the set_pmd so
that, when page fault find the pmd as trans huge we can be sure that
pgtable can be located at the offset.
variant of upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f
for 3.11 stable series
Signed-off-by: Aneesh Kumar K.V
---
arch/Kconfig | 3 +++
arch/powerpc/platforms/Kconfig.cputype | 1 +
mm/huge_memory.c | 12
3 files changed, 16 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index 1feb169274fe..c5863b35d054 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -368,6 +368,9 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
config HAVE_ARCH_SOFT_DIRTY
bool
+config ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ bool
+
config HAVE_MOD_ARCH_SPECIFIC
bool
help
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index 47d9a03dd415..d11a34be018d 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -71,6 +71,7 @@ config PPC_BOOK3S_64
select PPC_FPU
select PPC_HAVE_PMU_SUPPORT
select SYS_SUPPORTS_HUGETLBFS
+ select ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if PPC_64K_PAGES
config PPC_BOOK3E_64
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 12acb0ba7991..beaa7cc9de75 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1461,8 +1461,20 @@ int move_huge_pmd(struct vm_area_struct *vma, struct
vm_area_struct *new_vma,
ret = __pmd_trans_huge_lock(old_pmd, vma);
if (ret == 1) {
+#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ pgtable_t pgtable;
+#endif
pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
+#ifdef CONFIG_ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW
+ /*
+* Archs like ppc64 use pgtable to store per pmd
+* specific information. So when we switch the pmd,
+* we should also withdraw and deposit the pgtable
+*/
+ pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+ pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+#endif
set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
spin_unlock(&mm->page_table_lock);
}
--
1.8.5.3
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Re: [PATCH] powerpc: thp: Fix crash on mremap
On Tue, 14 Jan 2014 15:13:30 +1100 Benjamin Herrenschmidt wrote: > On Mon, 2014-01-13 at 14:17 -0800, Andrew Morton wrote: > > > Did this get fixed? > > Any chance you can Ack the patch on that thread ? > > http://thread.gmane.org/gmane.linux.kernel.mm/111809 > > So I can put it in powerpc -next with a CC stable ? Or if you tell me > tat Kirill Ack is sufficient then I'll go for it. yup, it looks OK to me from a non-ppc perspective. Please proceed as described. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] powerpc: thp: Fix crash on mremap
On Mon, 2014-01-13 at 14:17 -0800, Andrew Morton wrote: > Did this get fixed? Any chance you can Ack the patch on that thread ? http://thread.gmane.org/gmane.linux.kernel.mm/111809 So I can put it in powerpc -next with a CC stable ? Or if you tell me tat Kirill Ack is sufficient then I'll go for it. Cheers, Ben. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] powerpc: thp: Fix crash on mremap
On Mon, Jan 13, 2014 at 02:17:48PM -0800, Andrew Morton wrote: > On Thu, 2 Jan 2014 04:19:51 +0200 "Kirill A. Shutemov" > wrote: > > > On Wed, Jan 01, 2014 at 09:29:05PM +1100, Benjamin Herrenschmidt wrote: > > > On Wed, 2014-01-01 at 15:23 +0530, Aneesh Kumar K.V wrote: > > > > From: "Aneesh Kumar K.V" > > > > > > > > This patch fix the below crash > > > > > > > > NIP [c004cee4] .__hash_page_thp+0x2a4/0x440 > > > > LR [c00439ac] .hash_page+0x18c/0x5e0 > > > > ... > > > > Call Trace: > > > > [c00736103c40] [1b00] 0x1b00(unreliable) > > > > [437908.479693] [c00736103d50] [c00439ac] > > > > .hash_page+0x18c/0x5e0 > > > > [437908.479699] [c00736103e30] [c000924c] > > > > .do_hash_page+0x4c/0x58 > > > > > > > > On ppc64 we use the pgtable for storing the hpte slot information and > > > > store address to the pgtable at a constant offset (PTRS_PER_PMD) from > > > > pmd. On mremap, when we switch the pmd, we need to withdraw and deposit > > > > the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset > > > > from new pmd. > > > > > > > > We also want to move the withdraw and deposit before the set_pmd so > > > > that, when page fault find the pmd as trans huge we can be sure that > > > > pgtable can be located at the offset. > > > > > > Did this get fixed? New version: http://thread.gmane.org/gmane.linux.kernel.mm/111809 -- Kirill A. Shutemov ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] powerpc: thp: Fix crash on mremap
On Thu, 2 Jan 2014 04:19:51 +0200 "Kirill A. Shutemov" wrote: > On Wed, Jan 01, 2014 at 09:29:05PM +1100, Benjamin Herrenschmidt wrote: > > On Wed, 2014-01-01 at 15:23 +0530, Aneesh Kumar K.V wrote: > > > From: "Aneesh Kumar K.V" > > > > > > This patch fix the below crash > > > > > > NIP [c004cee4] .__hash_page_thp+0x2a4/0x440 > > > LR [c00439ac] .hash_page+0x18c/0x5e0 > > > ... > > > Call Trace: > > > [c00736103c40] [1b00] 0x1b00(unreliable) > > > [437908.479693] [c00736103d50] [c00439ac] > > > .hash_page+0x18c/0x5e0 > > > [437908.479699] [c00736103e30] [c000924c] > > > .do_hash_page+0x4c/0x58 > > > > > > On ppc64 we use the pgtable for storing the hpte slot information and > > > store address to the pgtable at a constant offset (PTRS_PER_PMD) from > > > pmd. On mremap, when we switch the pmd, we need to withdraw and deposit > > > the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset > > > from new pmd. > > > > > > We also want to move the withdraw and deposit before the set_pmd so > > > that, when page fault find the pmd as trans huge we can be sure that > > > pgtable can be located at the offset. > > > Did this get fixed? ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] powerpc: thp: Fix crash on mremap
On Wed, Jan 01, 2014 at 09:29:05PM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2014-01-01 at 15:23 +0530, Aneesh Kumar K.V wrote:
> > From: "Aneesh Kumar K.V"
> >
> > This patch fix the below crash
> >
> > NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
> > LR [c00439ac] .hash_page+0x18c/0x5e0
> > ...
> > Call Trace:
> > [c00736103c40] [1b00] 0x1b00(unreliable)
> > [437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
> > [437908.479699] [c00736103e30] [c000924c]
> > .do_hash_page+0x4c/0x58
> >
> > On ppc64 we use the pgtable for storing the hpte slot information and
> > store address to the pgtable at a constant offset (PTRS_PER_PMD) from
> > pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
> > the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
> > from new pmd.
> >
> > We also want to move the withdraw and deposit before the set_pmd so
> > that, when page fault find the pmd as trans huge we can be sure that
> > pgtable can be located at the offset.
> >
> > Signed-off-by: Aneesh Kumar K.V
> > ---
> > NOTE:
> > For other archs we would just be removing the pgtable from the list and
> > adding it back.
> > I didn't find an easy way to make it not do that without lots of #ifdef
> > around. Any
> > suggestion around that is welcome.
>
> What about
>
> - if (new_ptl != old_ptl) {
> + if (new_ptl != old_ptl || ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW) {
>
> Or something similar ?
Looks sane to me. Or something with IS_ENABLED(), if needed.
>
> Cheers,
> Ben.
>
> > mm/huge_memory.c | 21 ++---
> > 1 file changed, 10 insertions(+), 11 deletions(-)
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 7de1bf85f683..eb2e60d9ba45 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -1500,24 +1500,23 @@ int move_huge_pmd(struct vm_area_struct *vma,
> > struct vm_area_struct *new_vma,
> > */
> > ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
> > if (ret == 1) {
> > + pgtable_t pgtable;
> > +
> > new_ptl = pmd_lockptr(mm, new_pmd);
> > if (new_ptl != old_ptl)
> > spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
> > pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
> > VM_BUG_ON(!pmd_none(*new_pmd));
> > + /*
> > +* Archs like ppc64 use pgtable to store per pmd
> > +* specific information. So when we switch the pmd,
> > +* we should also withdraw and deposit the pgtable
> > +*/
> > + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
> > + pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> > set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
> > - if (new_ptl != old_ptl) {
> > - pgtable_t pgtable;
> > -
> > - /*
> > -* Move preallocated PTE page table if new_pmd is on
> > -* different PMD page table.
> > -*/
Please don't lose the comment.
> > - pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
> > - pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> > -
> > + if (new_ptl != old_ptl)
> > spin_unlock(new_ptl);
> > - }
> > spin_unlock(old_ptl);
> > }
> > out:
>
>
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Re: [PATCH] powerpc: thp: Fix crash on mremap
On Wed, 2014-01-01 at 15:23 +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V"
>
> This patch fix the below crash
>
> NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
> LR [c00439ac] .hash_page+0x18c/0x5e0
> ...
> Call Trace:
> [c00736103c40] [1b00] 0x1b00(unreliable)
> [437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
> [437908.479699] [c00736103e30] [c000924c] .do_hash_page+0x4c/0x58
>
> On ppc64 we use the pgtable for storing the hpte slot information and
> store address to the pgtable at a constant offset (PTRS_PER_PMD) from
> pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
> the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
> from new pmd.
>
> We also want to move the withdraw and deposit before the set_pmd so
> that, when page fault find the pmd as trans huge we can be sure that
> pgtable can be located at the offset.
>
> Signed-off-by: Aneesh Kumar K.V
> ---
> NOTE:
> For other archs we would just be removing the pgtable from the list and
> adding it back.
> I didn't find an easy way to make it not do that without lots of #ifdef
> around. Any
> suggestion around that is welcome.
What about
- if (new_ptl != old_ptl) {
+ if (new_ptl != old_ptl || ARCH_THP_MOVE_PMD_ALWAYS_WITHDRAW) {
Or something similar ?
Cheers,
Ben.
> mm/huge_memory.c | 21 ++---
> 1 file changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 7de1bf85f683..eb2e60d9ba45 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1500,24 +1500,23 @@ int move_huge_pmd(struct vm_area_struct *vma, struct
> vm_area_struct *new_vma,
>*/
> ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
> if (ret == 1) {
> + pgtable_t pgtable;
> +
> new_ptl = pmd_lockptr(mm, new_pmd);
> if (new_ptl != old_ptl)
> spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
> pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
> VM_BUG_ON(!pmd_none(*new_pmd));
> + /*
> + * Archs like ppc64 use pgtable to store per pmd
> + * specific information. So when we switch the pmd,
> + * we should also withdraw and deposit the pgtable
> + */
> + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
> + pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
> - if (new_ptl != old_ptl) {
> - pgtable_t pgtable;
> -
> - /*
> - * Move preallocated PTE page table if new_pmd is on
> - * different PMD page table.
> - */
> - pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
> - pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> -
> + if (new_ptl != old_ptl)
> spin_unlock(new_ptl);
> - }
> spin_unlock(old_ptl);
> }
> out:
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[PATCH] powerpc: thp: Fix crash on mremap
From: "Aneesh Kumar K.V"
This patch fix the below crash
NIP [c004cee4] .__hash_page_thp+0x2a4/0x440
LR [c00439ac] .hash_page+0x18c/0x5e0
...
Call Trace:
[c00736103c40] [1b00] 0x1b00(unreliable)
[437908.479693] [c00736103d50] [c00439ac] .hash_page+0x18c/0x5e0
[437908.479699] [c00736103e30] [c000924c] .do_hash_page+0x4c/0x58
On ppc64 we use the pgtable for storing the hpte slot information and
store address to the pgtable at a constant offset (PTRS_PER_PMD) from
pmd. On mremap, when we switch the pmd, we need to withdraw and deposit
the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset
from new pmd.
We also want to move the withdraw and deposit before the set_pmd so
that, when page fault find the pmd as trans huge we can be sure that
pgtable can be located at the offset.
Signed-off-by: Aneesh Kumar K.V
---
NOTE:
For other archs we would just be removing the pgtable from the list and adding
it back.
I didn't find an easy way to make it not do that without lots of #ifdef around.
Any
suggestion around that is welcome.
mm/huge_memory.c | 21 ++---
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7de1bf85f683..eb2e60d9ba45 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1500,24 +1500,23 @@ int move_huge_pmd(struct vm_area_struct *vma, struct
vm_area_struct *new_vma,
*/
ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
if (ret == 1) {
+ pgtable_t pgtable;
+
new_ptl = pmd_lockptr(mm, new_pmd);
if (new_ptl != old_ptl)
spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
+ /*
+* Archs like ppc64 use pgtable to store per pmd
+* specific information. So when we switch the pmd,
+* we should also withdraw and deposit the pgtable
+*/
+ pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+ pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
- if (new_ptl != old_ptl) {
- pgtable_t pgtable;
-
- /*
-* Move preallocated PTE page table if new_pmd is on
-* different PMD page table.
-*/
- pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
- pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
-
+ if (new_ptl != old_ptl)
spin_unlock(new_ptl);
- }
spin_unlock(old_ptl);
}
out:
--
1.8.3.2
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