From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + z3fold-fix-potential-race-in-z3fold_reclaim_page.patch added to -mm tree Date: Wed, 13 Sep 2017 14:45:12 -0700 Message-ID: <59b9a6e8.r5DvOcWHBYba7/mb%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:47230 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751465AbdIMVpN (ORCPT ); Wed, 13 Sep 2017 17:45:13 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: vitalywool@gmail.com, ddstreet@ieee.org, Oleksiy.Avramchenko@sony.com, mm-commits@vger.kernel.org The patch titled Subject: z3fold: fix potential race in z3fold_reclaim_page has been added to the -mm tree. Its filename is z3fold-fix-potential-race-in-z3fold_reclaim_page.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/z3fold-fix-potential-race-in-z3fold_reclaim_page.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/z3fold-fix-potential-race-in-z3fold_reclaim_page.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Vitaly Wool Subject: z3fold: fix potential race in z3fold_reclaim_page It is possible that on a (partially) unsuccessful page reclaim, kref_put() called in z3fold_reclaim_page() does not yield page release, but the page is released shortly afterwards by another thread. Then z3fold_reclaim_page() would try to list_add() that (released) page again which is obviously a bug. To avoid that, spin_lock() has to be taken earlier, before the kref_put() call mentioned earlier. Link: http://lkml.kernel.org/r/20170913162937.bfff21c7d12b12a5f47639fd@gmail.com Signed-off-by: Vitaly Wool Cc: Dan Streetman Cc: Signed-off-by: Andrew Morton --- mm/z3fold.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN mm/z3fold.c~z3fold-fix-potential-race-in-z3fold_reclaim_page mm/z3fold.c --- a/mm/z3fold.c~z3fold-fix-potential-race-in-z3fold_reclaim_page +++ a/mm/z3fold.c @@ -875,16 +875,18 @@ static int z3fold_reclaim_page(struct z3 goto next; } next: + spin_lock(&pool->lock); if (test_bit(PAGE_HEADLESS, &page->private)) { if (ret == 0) { + spin_unlock(&pool->lock); free_z3fold_page(page); return 0; } } else if (kref_put(&zhdr->refcount, release_z3fold_page)) { atomic64_dec(&pool->pages_nr); + spin_unlock(&pool->lock); return 0; } - spin_lock(&pool->lock); /* * Add to the beginning of LRU. _ Patches currently in -mm which might be from vitalywool@gmail.com are z3fold-fix-potential-race-in-z3fold_reclaim_page.patch