From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 89C0A6B003D for ; Fri, 8 May 2009 08:16:04 -0400 (EDT) Date: Fri, 8 May 2009 20:15:49 +0800 From: Wu Fengguang Subject: Re: [RFC][PATCH] vmscan: report vm_flags in page_referenced() Message-ID: <20090508121549.GA17077@localhost> References: <20090430195439.e02edc26.akpm@linux-foundation.org> <49FB01C1.6050204@redhat.com> <20090501123541.7983a8ae.akpm@linux-foundation.org> <20090503031539.GC5702@localhost> <1241432635.7620.4732.camel@twins> <20090507121101.GB20934@localhost> <20090507151039.GA2413@cmpxchg.org> <1241709466.11251.164.camel@twins> <20090508041700.GC8892@localhost> <28c262360905080509q333ec8acv2d2be69d99e1dfa3@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <28c262360905080509q333ec8acv2d2be69d99e1dfa3@mail.gmail.com> Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Peter Zijlstra , Johannes Weiner , Andrew Morton , Rik van Riel , "linux-kernel@vger.kernel.org" , "tytso@mit.edu" , "linux-mm@kvack.org" , Elladan , Nick Piggin , Christoph Lameter , KOSAKI Motohiro List-ID: On Fri, May 08, 2009 at 08:09:24PM +0800, Minchan Kim wrote: > On Fri, May 8, 2009 at 1:17 PM, Wu Fengguang 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 > >> > > > >> > > A A A A A /* page_referenced clears PageReferenced */ > >> > > A A A A A if (page_mapping_inuse(page) && > >> > > - A A A A A A page_referenced(page, 0, sc->mem_cgroup)) > >> > > + A A A A A A page_referenced(page, 0, sc->mem_cgroup)) { > >> > > + A A A A A A A A struct address_space *mapping = page_mapping(page); > >> > > + > >> > > A A A A A A A A A pgmoved++; > >> > > + A A A A A A A A if (mapping && test_bit(AS_EXEC, &mapping->flags)) { > >> > > + A A A A A A A A A A A A list_add(&page->lru, &l_active); > >> > > + A A A A A A A A A A A A continue; > >> > > + A A A A A A A A } > >> > > + A A A A } > >> > > >> > Since we walk the VMAs in page_referenced anyway, wouldn't it be > >> > better to check if one of them is executable? A This would even work > >> > for executable anon pages. A 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 > > --- > > A include/linux/rmap.h | A A 5 +++-- > > A mm/rmap.c A A A A A A | A 30 +++++++++++++++++++++--------- > > A mm/vmscan.c A A A A A | A A 7 +++++-- > > A 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 > > A /* > > A * Called from mm/vmscan.c to handle paging out > > A */ > > -int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt); > > +int page_referenced(struct page *, int is_locked, > > + A A A A A A A A A A A struct mem_cgroup *cnt, unsigned long *vm_flags); > > A int try_to_unmap(struct page *, int ignore_refs); > > > > A /* > > @@ -128,7 +129,7 @@ int page_wrprotect(struct page *page, in > > A #define anon_vma_prepare(vma) A (0) > > A #define anon_vma_link(vma) A A do {} while (0) > > > > -#define page_referenced(page,l,cnt) TestClearPageReferenced(page) > > +#define page_referenced(page, locked, cnt, flags) TestClearPageReferenced(page) > > A #define try_to_unmap(page, refs) SWAP_FAIL > > > > A 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 > > A * repeatedly from either page_referenced_anon or page_referenced_file. > > A */ > > A static int page_referenced_one(struct page *page, > > - A A A struct vm_area_struct *vma, unsigned int *mapcount) > > + A A A A A A A A A A A A A A A struct vm_area_struct *vma, > > + A A A A A A A A A A A A A A A unsigned int *mapcount) > > A { > > A A A A struct mm_struct *mm = vma->vm_mm; > > A A A A unsigned long address; > > @@ -385,7 +386,8 @@ out: > > A } > > > > A static int page_referenced_anon(struct page *page, > > - A A A A A A A A A A A A A A A struct mem_cgroup *mem_cont) > > + A A A A A A A A A A A A A A A struct mem_cgroup *mem_cont, > > + A A A A A A A A A A A A A A A unsigned long *vm_flags) > > A { > > A A A A unsigned int mapcount; > > A A A A struct anon_vma *anon_vma; > > @@ -406,6 +408,7 @@ static int page_referenced_anon(struct p > > A A A A A A A A if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) > > A A A A A A A A A A A A continue; > > A A A A A A A A referenced += page_referenced_one(page, vma, &mapcount); > > + A A A A A A A *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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org