| Message ID | 20181012160953.5841-1-jglisse@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/thp: fix call to mmu_notifier in set_pmd_migration_entry() | expand |
On 12 Oct 2018, at 12:09, jglisse@redhat.com wrote: > From: Jérôme Glisse <jglisse@redhat.com> > > Inside set_pmd_migration_entry() we are holding page table locks and > thus we can not sleep so we can not call invalidate_range_start/end() > > So remove call to mmu_notifier_invalidate_range_start/end() and add > call to mmu_notifier_invalidate_range(). Note that we are already > calling mmu_notifier_invalidate_range_start/end() inside the function > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > Reported-by: Andrea Arcangeli <aarcange@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Zi Yan <zi.yan@cs.rutgers.edu> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> > Cc: Dave Hansen <dave.hansen@intel.com> > Cc: David Nellans <dnellans@nvidia.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Andrea Arcangeli <aarcange@redhat.com> > --- > mm/huge_memory.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 533f9b00147d..93cb80fe12cb 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > if (!(pvmw->pmd && !pvmw->pte)) > return; > > - mmu_notifier_invalidate_range_start(mm, address, > - address + HPAGE_PMD_SIZE); > - > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > pmdval = *pvmw->pmd; > pmdp_invalidate(vma, address, pvmw->pmd); > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > if (pmd_soft_dirty(pmdval)) > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); > page_remove_rmap(page, true); > put_page(page); > - > - mmu_notifier_invalidate_range_end(mm, address, > - address + HPAGE_PMD_SIZE); > } > > void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) > -- > 2.17.2 Yes, these are the redundant calls to mmu_notifier_invalidate_range_start/end() in set_pmd_migration_entry(). Thanks for the patch. Fixes: 616b8371539a6 (mm: thp: enable thp migration in generic path) Reviewed-by: Zi Yan <zi.yan@cs.rutgers.edu> — Best Regards, Yan Zi
On Fri 12-10-18 12:09:53, jglisse@redhat.com wrote: > From: Jérôme Glisse <jglisse@redhat.com> > > Inside set_pmd_migration_entry() we are holding page table locks and > thus we can not sleep so we can not call invalidate_range_start/end() > > So remove call to mmu_notifier_invalidate_range_start/end() and add > call to mmu_notifier_invalidate_range(). Note that we are already > calling mmu_notifier_invalidate_range_start/end() inside the function > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > Reported-by: Andrea Arcangeli <aarcange@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Zi Yan <zi.yan@cs.rutgers.edu> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> > Cc: Dave Hansen <dave.hansen@intel.com> > Cc: David Nellans <dnellans@nvidia.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Andrea Arcangeli <aarcange@redhat.com> Is this worth backporting to stable trees? The patch looks good to me Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/huge_memory.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 533f9b00147d..93cb80fe12cb 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > if (!(pvmw->pmd && !pvmw->pte)) > return; > > - mmu_notifier_invalidate_range_start(mm, address, > - address + HPAGE_PMD_SIZE); > - > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > pmdval = *pvmw->pmd; > pmdp_invalidate(vma, address, pvmw->pmd); > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > if (pmd_soft_dirty(pmdval)) > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); > page_remove_rmap(page, true); > put_page(page); > - > - mmu_notifier_invalidate_range_end(mm, address, > - address + HPAGE_PMD_SIZE); > } > > void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) > -- > 2.17.2
On Fri, Oct 12, 2018 at 06:55:48PM +0200, Michal Hocko wrote: > On Fri 12-10-18 12:09:53, jglisse@redhat.com wrote: > > From: Jérôme Glisse <jglisse@redhat.com> > > > > Inside set_pmd_migration_entry() we are holding page table locks and > > thus we can not sleep so we can not call invalidate_range_start/end() > > > > So remove call to mmu_notifier_invalidate_range_start/end() and add > > call to mmu_notifier_invalidate_range(). Note that we are already > > calling mmu_notifier_invalidate_range_start/end() inside the function > > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > > Reported-by: Andrea Arcangeli <aarcange@redhat.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Zi Yan <zi.yan@cs.rutgers.edu> > > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> > > Cc: Dave Hansen <dave.hansen@intel.com> > > Cc: David Nellans <dnellans@nvidia.com> > > Cc: Ingo Molnar <mingo@elte.hu> > > Cc: Mel Gorman <mgorman@techsingularity.net> > > Cc: Minchan Kim <minchan@kernel.org> > > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Michal Hocko <mhocko@kernel.org> > > Cc: Andrea Arcangeli <aarcange@redhat.com> > > Is this worth backporting to stable trees? Yes it is i forgot to cc stable :( > > The patch looks good to me > Acked-by: Michal Hocko <mhocko@suse.com> > > > --- > > mm/huge_memory.c | 7 +------ > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index 533f9b00147d..93cb80fe12cb 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > if (!(pvmw->pmd && !pvmw->pte)) > > return; > > > > - mmu_notifier_invalidate_range_start(mm, address, > > - address + HPAGE_PMD_SIZE); > > - > > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > > pmdval = *pvmw->pmd; > > pmdp_invalidate(vma, address, pvmw->pmd); > > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > if (pmd_soft_dirty(pmdval)) > > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); > > page_remove_rmap(page, true); > > put_page(page); > > - > > - mmu_notifier_invalidate_range_end(mm, address, > > - address + HPAGE_PMD_SIZE); > > } > > > > void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) > > -- > > 2.17.2 > > -- > Michal Hocko > SUSE Labs
Hello, On Fri, Oct 12, 2018 at 12:20:54PM -0400, Zi Yan wrote: > On 12 Oct 2018, at 12:09, jglisse@redhat.com wrote: > > > From: Jérôme Glisse <jglisse@redhat.com> > > > > Inside set_pmd_migration_entry() we are holding page table locks and > > thus we can not sleep so we can not call invalidate_range_start/end() > > > > So remove call to mmu_notifier_invalidate_range_start/end() and add > > call to mmu_notifier_invalidate_range(). Note that we are already Why the call to mmu_notifier_invalidate_range if we're under range_start and followed by range_end? (it's not _range_only_end, if it was _range_only_end the above would be needed) > > calling mmu_notifier_invalidate_range_start/end() inside the function > > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > > Reported-by: Andrea Arcangeli <aarcange@redhat.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Zi Yan <zi.yan@cs.rutgers.edu> > > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> > > Cc: Dave Hansen <dave.hansen@intel.com> > > Cc: David Nellans <dnellans@nvidia.com> > > Cc: Ingo Molnar <mingo@elte.hu> > > Cc: Mel Gorman <mgorman@techsingularity.net> > > Cc: Minchan Kim <minchan@kernel.org> > > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Michal Hocko <mhocko@kernel.org> > > Cc: Andrea Arcangeli <aarcange@redhat.com> > > --- > > mm/huge_memory.c | 7 +------ > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index 533f9b00147d..93cb80fe12cb 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > if (!(pvmw->pmd && !pvmw->pte)) > > return; > > > > - mmu_notifier_invalidate_range_start(mm, address, > > - address + HPAGE_PMD_SIZE); > > - > > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > > pmdval = *pvmw->pmd; > > pmdp_invalidate(vma, address, pvmw->pmd); > > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > if (pmd_soft_dirty(pmdval)) > > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); It's not obvious why it's needed, if it's needed maybe a comment can be added. > > page_remove_rmap(page, true); > > put_page(page); > > - > > - mmu_notifier_invalidate_range_end(mm, address, > > - address + HPAGE_PMD_SIZE); > > } > > > > void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) > > -- > > 2.17.2 > > Yes, these are the redundant calls to mmu_notifier_invalidate_range_start/end() > in set_pmd_migration_entry(). Thanks for the patch. They're not just redundant, it's called in non blockable path with __mmu_notifier_invalidate_range_start(blockable=true). Furthermore mmu notifier API doesn't support nesting. KVM is actually robust against the nesting: kvm->mmu_notifier_count++; kvm->mmu_notifier_count--; and KVM is always fine with non blockable calls, but that's not universally true for all mmu notifier users. Thanks, Andrea
On Fri, Oct 12, 2018 at 01:24:22PM -0400, Andrea Arcangeli wrote: > Hello, > > On Fri, Oct 12, 2018 at 12:20:54PM -0400, Zi Yan wrote: > > On 12 Oct 2018, at 12:09, jglisse@redhat.com wrote: > > > > > From: Jérôme Glisse <jglisse@redhat.com> > > > > > > Inside set_pmd_migration_entry() we are holding page table locks and > > > thus we can not sleep so we can not call invalidate_range_start/end() > > > > > > So remove call to mmu_notifier_invalidate_range_start/end() and add > > > call to mmu_notifier_invalidate_range(). Note that we are already > > Why the call to mmu_notifier_invalidate_range if we're under > range_start and followed by range_end? (it's not _range_only_end, if > it was _range_only_end the above would be needed) I wanted to be extra safe and accept to over invalidate. You are right that it is not strictly necessary. I am fine with removing it. > > > > calling mmu_notifier_invalidate_range_start/end() inside the function > > > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > > > > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > > > Reported-by: Andrea Arcangeli <aarcange@redhat.com> > > > Cc: Andrew Morton <akpm@linux-foundation.org> > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > Cc: Zi Yan <zi.yan@cs.rutgers.edu> > > > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > > Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> > > > Cc: Dave Hansen <dave.hansen@intel.com> > > > Cc: David Nellans <dnellans@nvidia.com> > > > Cc: Ingo Molnar <mingo@elte.hu> > > > Cc: Mel Gorman <mgorman@techsingularity.net> > > > Cc: Minchan Kim <minchan@kernel.org> > > > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > > > Cc: Thomas Gleixner <tglx@linutronix.de> > > > Cc: Vlastimil Babka <vbabka@suse.cz> > > > Cc: Michal Hocko <mhocko@kernel.org> > > > Cc: Andrea Arcangeli <aarcange@redhat.com> > > > --- > > > mm/huge_memory.c | 7 +------ > > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > > index 533f9b00147d..93cb80fe12cb 100644 > > > --- a/mm/huge_memory.c > > > +++ b/mm/huge_memory.c > > > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > > if (!(pvmw->pmd && !pvmw->pte)) > > > return; > > > > > > - mmu_notifier_invalidate_range_start(mm, address, > > > - address + HPAGE_PMD_SIZE); > > > - > > > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > > > pmdval = *pvmw->pmd; > > > pmdp_invalidate(vma, address, pvmw->pmd); > > > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > > if (pmd_soft_dirty(pmdval)) > > > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > > > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > > > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); > > It's not obvious why it's needed, if it's needed maybe a comment can > be added. We can remove it. Should i post a v2 without it ? Cheers, Jérôme
On Fri, Oct 12, 2018 at 01:35:19PM -0400, Jerome Glisse wrote: > On Fri, Oct 12, 2018 at 01:24:22PM -0400, Andrea Arcangeli wrote: > > Hello, > > > > On Fri, Oct 12, 2018 at 12:20:54PM -0400, Zi Yan wrote: > > > On 12 Oct 2018, at 12:09, jglisse@redhat.com wrote: > > > > > > > From: Jérôme Glisse <jglisse@redhat.com> > > > > > > > > Inside set_pmd_migration_entry() we are holding page table locks and > > > > thus we can not sleep so we can not call invalidate_range_start/end() > > > > > > > > So remove call to mmu_notifier_invalidate_range_start/end() and add > > > > call to mmu_notifier_invalidate_range(). Note that we are already > > > > Why the call to mmu_notifier_invalidate_range if we're under > > range_start and followed by range_end? (it's not _range_only_end, if > > it was _range_only_end the above would be needed) > > I wanted to be extra safe and accept to over invalidate. You are right > that it is not strictly necessary. I am fine with removing it. If it's superfluous, I'd generally prefer strict code unless there's a very explicit comment about it that says it's actually superfluous. Otherwise after a while we don't know why it was added there. > We can remove it. Should i post a v2 without it ? That's fine with me yes. Thanks, Andrea
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 533f9b00147d..93cb80fe12cb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, if (!(pvmw->pmd && !pvmw->pte)) return; - mmu_notifier_invalidate_range_start(mm, address, - address + HPAGE_PMD_SIZE); - flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); pmdval = *pvmw->pmd; pmdp_invalidate(vma, address, pvmw->pmd); @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, if (pmd_soft_dirty(pmdval)) pmdswp = pmd_swp_mksoft_dirty(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); page_remove_rmap(page, true); put_page(page); - - mmu_notifier_invalidate_range_end(mm, address, - address + HPAGE_PMD_SIZE); } void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)