Messages in this thread | | | Date | Fri, 8 May 2009 20:15:49 +0800 | From | Wu Fengguang <> | Subject | Re: [RFC][PATCH] vmscan: report vm_flags in page_referenced() |
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On Fri, May 08, 2009 at 08:09:24PM +0800, Minchan Kim wrote: > On Fri, May 8, 2009 at 1:17 PM, Wu Fengguang <fengguang.wu@intel.com> wrote: > > On Thu, May 07, 2009 at 11:17:46PM +0800, Peter Zijlstra wrote: > >> On Thu, 2009-05-07 at 17:10 +0200, Johannes Weiner wrote: > >> > >> > > @@ -1269,8 +1270,15 @@ static void shrink_active_list(unsigned > >> > > > >> > > /* page_referenced clears PageReferenced */ > >> > > if (page_mapping_inuse(page) && > >> > > - page_referenced(page, 0, sc->mem_cgroup)) > >> > > + page_referenced(page, 0, sc->mem_cgroup)) { > >> > > + struct address_space *mapping = page_mapping(page); > >> > > + > >> > > pgmoved++; > >> > > + if (mapping && test_bit(AS_EXEC, &mapping->flags)) { > >> > > + list_add(&page->lru, &l_active); > >> > > + continue; > >> > > + } > >> > > + } > >> > > >> > Since we walk the VMAs in page_referenced anyway, wouldn't it be > >> > better to check if one of them is executable? This would even work > >> > for executable anon pages. After all, there are applications that cow > >> > executable mappings (sbcl and other language environments that use an > >> > executable, run-time modified core image come to mind). > >> > >> Hmm, like provide a vm_flags mask along to page_referenced() to only > >> account matching vmas... seems like a sensible idea. > > > > Here is a quick patch for your opinions. Compile tested. > > > > With the added vm_flags reporting, the mlock=>unevictable logic can > > possibly be made more straightforward. > > > > Thanks, > > Fengguang > > --- > > vmscan: report vm_flags in page_referenced() > > > > This enables more informed reclaim heuristics, eg. to protect executable > > file pages more aggressively. > > > > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> > > --- > > include/linux/rmap.h | 5 +++-- > > mm/rmap.c | 30 +++++++++++++++++++++--------- > > mm/vmscan.c | 7 +++++-- > > 3 files changed, 29 insertions(+), 13 deletions(-) > > > > --- linux.orig/include/linux/rmap.h > > +++ linux/include/linux/rmap.h > > @@ -83,7 +83,8 @@ static inline void page_dup_rmap(struct > > /* > > * Called from mm/vmscan.c to handle paging out > > */ > > -int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt); > > +int page_referenced(struct page *, int is_locked, > > + struct mem_cgroup *cnt, unsigned long *vm_flags); > > int try_to_unmap(struct page *, int ignore_refs); > > > > /* > > @@ -128,7 +129,7 @@ int page_wrprotect(struct page *page, in > > #define anon_vma_prepare(vma) (0) > > #define anon_vma_link(vma) do {} while (0) > > > > -#define page_referenced(page,l,cnt) TestClearPageReferenced(page) > > +#define page_referenced(page, locked, cnt, flags) TestClearPageReferenced(page) > > #define try_to_unmap(page, refs) SWAP_FAIL > > > > static inline int page_mkclean(struct page *page) > > --- linux.orig/mm/rmap.c > > +++ linux/mm/rmap.c > > @@ -333,7 +333,8 @@ static int page_mapped_in_vma(struct pag > > * repeatedly from either page_referenced_anon or page_referenced_file. > > */ > > static int page_referenced_one(struct page *page, > > - struct vm_area_struct *vma, unsigned int *mapcount) > > + struct vm_area_struct *vma, > > + unsigned int *mapcount) > > { > > struct mm_struct *mm = vma->vm_mm; > > unsigned long address; > > @@ -385,7 +386,8 @@ out: > > } > > > > static int page_referenced_anon(struct page *page, > > - struct mem_cgroup *mem_cont) > > + struct mem_cgroup *mem_cont, > > + unsigned long *vm_flags) > > { > > unsigned int mapcount; > > struct anon_vma *anon_vma; > > @@ -406,6 +408,7 @@ static int page_referenced_anon(struct p > > if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) > > continue; > > referenced += page_referenced_one(page, vma, &mapcount); > > + *vm_flags |= vma->vm_flags; > > Sometime this vma don't contain the anon page. > That's why we need page_check_address. > For such a case, wrong *vm_flag cause be harmful to reclaim. > It can be happen in your first class citizen patch, I think.
Yes I'm aware of that - the VMA area covers that page, but have no pte actually installed for that page. That should be OK - the presentation of such VMA is a good indication of it being some executable text. -- 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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