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| Started by | Minchan Kim <minchan@kernel.org> |
|---|---|
| First post | 2015-10-13 05:00 +0200 |
| Last post | 2015-10-13 11:10 +0200 |
| Articles | 5 — 3 participants |
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[PATCH v2] thp: use is_zero_pfn only after pte_present check Minchan Kim <minchan@kernel.org> - 2015-10-13 05:00 +0200
Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-13 08:00 +0200
Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check Minchan Kim <minchan@kernel.org> - 2015-10-13 08:30 +0200
Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check Vlastimil Babka <vbabka@suse.cz> - 2015-10-13 09:30 +0200
Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check Minchan Kim <minchan@kernel.org> - 2015-10-13 11:10 +0200
| From | Minchan Kim <minchan@kernel.org> |
|---|---|
| Date | 2015-10-13 05:00 +0200 |
| Subject | [PATCH v2] thp: use is_zero_pfn only after pte_present check |
| Message-ID | <qiXYJ-1Ik-1@gated-at.bofh.it> |
Use is_zero_pfn on pteval only after pte_present check on pteval
(It might be better idea to introduce is_zero_pte where checks
pte_present first). Otherwise, it could work with swap or
migration entry and if pte_pfn's result is equal to zero_pfn
by chance, we lose user's data in __collapse_huge_page_copy.
So if you're luck, the application is segfaulted and finally you
could see below message when the application is exit.
BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3
Cc: <stable@vger.kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
Hello Greg,
This patch should go to -stable but when you will apply it
after merging of linus tree, it will be surely conflicted due
to userfaultfd part.
I want to know how to handle it.
Thanks.
mm/huge_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4b06b8db9df2..bbac913f96bc 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2206,7 +2206,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
_pte++, address += PAGE_SIZE) {
pte_t pteval = *_pte;
- if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+ if (pte_none(pteval) || (pte_present(pteval) &&
+ is_zero_pfn(pte_pfn(pteval)))) {
if (!userfaultfd_armed(vma) &&
++none_or_zero <= khugepaged_max_ptes_none)
continue;
--
1.9.1
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| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Date | 2015-10-13 08:00 +0200 |
| Message-ID | <qj0MW-5PO-13@gated-at.bofh.it> |
| In reply to | #1245305 |
On Tue, Oct 13, 2015 at 11:38:38AM +0900, Minchan Kim wrote: > Use is_zero_pfn on pteval only after pte_present check on pteval > (It might be better idea to introduce is_zero_pte where checks > pte_present first). Otherwise, it could work with swap or > migration entry and if pte_pfn's result is equal to zero_pfn > by chance, we lose user's data in __collapse_huge_page_copy. > So if you're luck, the application is segfaulted and finally you > could see below message when the application is exit. > > BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3 > > Cc: <stable@vger.kernel.org> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> > Signed-off-by: Minchan Kim <minchan@kernel.org> > --- > Hello Greg, > > This patch should go to -stable but when you will apply it > after merging of linus tree, it will be surely conflicted due > to userfaultfd part. > > I want to know how to handle it. You will get an automated email saying it didn't apply and then you provide a backported version. Or you send a properly backported version to stable@vger.kernel.org before then, with the git commit id of the patch in Linus's tree. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Minchan Kim <minchan@kernel.org> |
|---|---|
| Date | 2015-10-13 08:30 +0200 |
| Message-ID | <qj1fX-6Co-5@gated-at.bofh.it> |
| In reply to | #1245362 |
On Mon, Oct 12, 2015 at 10:41:24PM -0700, Greg Kroah-Hartman wrote: > On Tue, Oct 13, 2015 at 11:38:38AM +0900, Minchan Kim wrote: > > Use is_zero_pfn on pteval only after pte_present check on pteval > > (It might be better idea to introduce is_zero_pte where checks > > pte_present first). Otherwise, it could work with swap or > > migration entry and if pte_pfn's result is equal to zero_pfn > > by chance, we lose user's data in __collapse_huge_page_copy. > > So if you're luck, the application is segfaulted and finally you > > could see below message when the application is exit. > > > > BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3 > > > > Cc: <stable@vger.kernel.org> > > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> > > Signed-off-by: Minchan Kim <minchan@kernel.org> > > --- > > Hello Greg, > > > > This patch should go to -stable but when you will apply it > > after merging of linus tree, it will be surely conflicted due > > to userfaultfd part. > > > > I want to know how to handle it. > > You will get an automated email saying it didn't apply and then you > provide a backported version. Or you send a properly backported version > to stable@vger.kernel.org before then, with the git commit id of the > patch in Linus's tree. Okay, I will send a right version when I received automatd email. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Vlastimil Babka <vbabka@suse.cz> |
|---|---|
| Date | 2015-10-13 09:30 +0200 |
| Message-ID | <qj2c2-80M-7@gated-at.bofh.it> |
| In reply to | #1245305 |
On 10/13/2015 04:38 AM, Minchan Kim wrote:
> Use is_zero_pfn on pteval only after pte_present check on pteval
> (It might be better idea to introduce is_zero_pte where checks
> pte_present first). Otherwise, it could work with swap or
> migration entry and if pte_pfn's result is equal to zero_pfn
> by chance, we lose user's data in __collapse_huge_page_copy.
> So if you're luck, the application is segfaulted and finally you
> could see below message when the application is exit.
>
> BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3
>
> Cc: <stable@vger.kernel.org>
More specific:
Cc: <stable@vger.kernel.org> # 4.1+
Fixes: ca0984caa823 ("mm: incorporate zero pages into transparent huge
pages")
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> Hello Greg,
>
> This patch should go to -stable but when you will apply it
> after merging of linus tree, it will be surely conflicted due
> to userfaultfd part.
>
> I want to know how to handle it.
>
> Thanks.
>
> mm/huge_memory.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4b06b8db9df2..bbac913f96bc 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2206,7 +2206,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
> _pte++, address += PAGE_SIZE) {
> pte_t pteval = *_pte;
> - if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
> + if (pte_none(pteval) || (pte_present(pteval) &&
> + is_zero_pfn(pte_pfn(pteval)))) {
> if (!userfaultfd_armed(vma) &&
> ++none_or_zero <= khugepaged_max_ptes_none)
> continue;
>
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| From | Minchan Kim <minchan@kernel.org> |
|---|---|
| Date | 2015-10-13 11:10 +0200 |
| Message-ID | <qj3KP-1Wm-37@gated-at.bofh.it> |
| In reply to | #1245407 |
On Tue, Oct 13, 2015 at 09:28:23AM +0200, Vlastimil Babka wrote:
> On 10/13/2015 04:38 AM, Minchan Kim wrote:
> >Use is_zero_pfn on pteval only after pte_present check on pteval
> >(It might be better idea to introduce is_zero_pte where checks
> >pte_present first). Otherwise, it could work with swap or
> >migration entry and if pte_pfn's result is equal to zero_pfn
> >by chance, we lose user's data in __collapse_huge_page_copy.
> >So if you're luck, the application is segfaulted and finally you
> >could see below message when the application is exit.
> >
> >BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3
> >
> >Cc: <stable@vger.kernel.org>
>
> More specific:
> Cc: <stable@vger.kernel.org> # 4.1+
> Fixes: ca0984caa823 ("mm: incorporate zero pages into transparent
> huge pages")
>
> >Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
Thanks for the detail and review, Vlastimil.
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