On Sat 28-02-15 10:11:13, Wang, Yalin wrote: > > -----Original Message----- > > From: Michal Hocko [mailto:mstsxfx@xxxxxxxxx] On Behalf Of Michal Hocko > > Sent: Saturday, February 28, 2015 5:03 AM > > To: Wang, Yalin > > Cc: 'Minchan Kim'; Andrew Morton; linux-kernel@xxxxxxxxxxxxxxx; linux- > > mm@xxxxxxxxx; Rik van Riel; Johannes Weiner; Mel Gorman; Shaohua Li > > Subject: Re: [RFC] mm: change mm_advise_free to clear page dirty > > > > On Fri 27-02-15 11:37:18, Wang, Yalin wrote: > > > This patch add ClearPageDirty() to clear AnonPage dirty flag, > > > the Anonpage mapcount must be 1, so that this page is only used by > > > the current process, not shared by other process like fork(). > > > if not clear page dirty for this anon page, the page will never be > > > treated as freeable. > > > > Very well spotted! I haven't noticed that during the review. > > > > > Signed-off-by: Yalin Wang <yalin.wang@xxxxxxxxxxxxxx> > > > --- > > > mm/madvise.c | 15 +++++---------- > > > 1 file changed, 5 insertions(+), 10 deletions(-) > > > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > > index 6d0fcb8..257925a 100644 > > > --- a/mm/madvise.c > > > +++ b/mm/madvise.c > > > @@ -297,22 +297,17 @@ static int madvise_free_pte_range(pmd_t *pmd, > > unsigned long addr, > > > continue; > > > > > > page = vm_normal_page(vma, addr, ptent); > > > - if (!page) > > > + if (!page || !PageAnon(page) || !trylock_page(page)) > > > continue; > > > > PageAnon check seems to be redundant because we are not allowing > > MADV_FREE on any !anon private mappings AFAIR. > I only see this check: > /* MADV_FREE works for only anon vma at the moment */ > if (vma->vm_file) > return -EINVAL; > > but for file private map, there are also AnonPage sometimes, AFAIR MADV_FREE was intended only for private anon mappings. What would be the use case for MADV_FREE on file backed private mappings? [...] -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>