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Date: Mon, 20 Dec 2010 12:03:35 +0900 (JST) From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> To: Minchan Kim <minchan.kim@...il.com> Cc: kosaki.motohiro@...fujitsu.com, Andrew Morton <akpm@...ux-foundation.org>, linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Nick Piggin <npiggin@...e.de>, Al Viro <viro@...iv.linux.org.uk> Subject: Re: [RFC 5/5] truncate: Remove unnecessary page release > On Mon, Dec 20, 2010 at 11:32 AM, KOSAKI Motohiro > <kosaki.motohiro@...fujitsu.com> wrote: > >> On Mon, Dec 20, 2010 at 11:21 AM, KOSAKI Motohiro > >> <kosaki.motohiro@...fujitsu.com> wrote: > >> >> This patch series changes remove_from_page_cache's page ref counting > >> >> rule. page cache ref count is decreased in remove_from_page_cache. > >> >> So we don't need call again in caller context. > >> >> > >> >> Cc: Nick Piggin <npiggin@...e.de> > >> >> Cc: Al Viro <viro@...iv.linux.org.uk> > >> >> Cc: linux-mm@...ck.org > >> >> Signed-off-by: Minchan Kim <minchan.kim@...il.com> > >> >> --- > >> >> mm/truncate.c | 1 - > >> >> 1 files changed, 0 insertions(+), 1 deletions(-) > >> >> > >> >> diff --git a/mm/truncate.c b/mm/truncate.c > >> >> index 9ee5673..8decb93 100644 > >> >> --- a/mm/truncate.c > >> >> +++ b/mm/truncate.c > >> >> @@ -114,7 +114,6 @@ truncate_complete_page(struct address_space *mapping, struct page *page) > >> >> * calls cleancache_put_page (and note page->mapping is now NULL) > >> >> */ > >> >> cleancache_flush_page(mapping, page); > >> >> - page_cache_release(page); /* pagecache ref */ > >> >> return 0; > >> > > >> > Do we _always_ have stable page reference here? IOW, I can assume > >> > >> I think so. > >> Because the page is locked so caller have to hold a ref to unlock it. > > > > Hmm... > > > > Perhaps, I'm missing something. But I think __memory_failure() only lock > > compaund_head page. not all. example. > > The page passed truncate_complete_page is only head page? > Is it possible to pass the page which isn't head of compound in > truncate_complete_page? I dunno, really. My five miniture grep found following logic. therefore I asked you. __memory_failure() { p = pfn_to_page(pfn); hpage = compound_head(p); (snip) res = -EBUSY; for (ps = error_states;; ps++) { if ((p->flags & ps->mask) == ps->res) { res = page_action(ps, p, pfn); // call truncate here break; } } out: unlock_page(hpage); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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