mm: migration: do not lose soft dirty bit if page is in migration state (c3d16e16) · Commits · 戴 / test

If page migration is turned on in config and the page is migrating, we may lose the soft dirty bit. If fork and mprotect are called on migrating pages (once migration is complete) pages do not obtain the soft dirty bit in the correspond pte entries. Fix it adding an appropriate test on swap entries. Signed-off-by:

Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: <stable@vger.kernel.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -837,6 +837,8 @@ copy_one_pte(struct mm_struct dst_mm, struct mm_struct src_mm,
		*/
		make_migration_entry_read(&entry);
		pte = swp_entry_to_pte(entry);
		if (pte_swp_soft_dirty(*src_pte))
		pte = pte_swp_mksoft_dirty(pte);
		set_pte_at(src_mm, addr, src_pte, pte);
		}
		}

mm/migrate.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -161,6 +161,8 @@ static int remove_migration_pte(struct page new, struct vm_area_struct vma,

		get_page(new);
		pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
		if (pte_swp_soft_dirty(*ptep))
		pte = pte_mksoft_dirty(pte);
		if (is_write_migration_entry(entry))
		pte = pte_mkwrite(pte);
		#ifdef CONFIG_HUGETLB_PAGE

mm/mprotect.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -94,13 +94,16 @@ static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
		swp_entry_t entry = pte_to_swp_entry(oldpte);

		if (is_write_migration_entry(entry)) {
		pte_t newpte;
		/*
		* A protection check is difficult so
		* just be safe and disable write
		*/
		make_migration_entry_read(&entry);
		set_pte_at(mm, addr, pte,
		swp_entry_to_pte(entry));
		newpte = swp_entry_to_pte(entry);
		if (pte_swp_soft_dirty(oldpte))
		newpte = pte_swp_mksoft_dirty(newpte);
		set_pte_at(mm, addr, pte, newpte);
		}
		pages++;
		}

Admin message