From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id D21DA828ED for ; Fri, 8 Jan 2016 18:36:27 -0500 (EST) Received: by mail-pa0-f54.google.com with SMTP id ho8so28799896pac.2 for ; Fri, 08 Jan 2016 15:36:27 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id u16si8057724pfa.225.2016.01.08.15.36.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Jan 2016 15:36:27 -0800 (PST) Date: Fri, 8 Jan 2016 15:36:26 -0800 From: Andrew Morton Subject: Re: [PATCH v1] mm: soft-offline: check return value in second __get_any_page() call Message-Id: <20160108153626.16332573d71cdfcdbc1637cd@linux-foundation.org> In-Reply-To: <20160108075158.GA28640@hori1.linux.bs1.fc.nec.co.jp> References: <1452237748-10822-1-git-send-email-n-horiguchi@ah.jp.nec.com> <20160108075158.GA28640@hori1.linux.bs1.fc.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: Andi Kleen , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Naoya Horiguchi On Fri, 8 Jan 2016 07:51:59 +0000 Naoya Horiguchi wrote: > > [ 52.600579] [] SyS_madvise+0x6bc/0x6f0 > > [ 52.600579] [] ? fpu__restore_sig+0xcc/0x320 > > [ 52.600579] [] ? do_sigaction+0x73/0x1b0 > > [ 52.600579] [] ? __set_task_blocked+0x32/0x70 > > [ 52.600579] [] entry_SYSCALL_64_fastpath+0x12/0x6a > > [ 52.600579] Code: 8b fc ff ff 5b 5d c3 48 89 df e8 b0 fa ff ff 48 89 df 31 f6 e8 c6 7d ff ff 5b 5d c3 48 c7 c6 08 54 a2 81 48 89 df e8 a4 c5 01 00 <0f> 0b 66 90 66 66 66 66 90 55 48 89 e5 41 55 41 54 53 48 8b 47 > > [ 52.600579] RIP [] put_page+0x5c/0x60 > > [ 52.600579] RSP > > > > The root cause resides in get_any_page() which retries to get a refcount of > > the page to be soft-offlined. This function calls put_hwpoison_page(), expecting > > that the target page is putback to LRU list. But it can be also freed to buddy. > > So the second check need to care about such case. > > > > Fixes: af8fae7c0886 ("mm/memory-failure.c: clean up soft_offline_page()") > > Signed-off-by: Naoya Horiguchi > > Cc: stable@vger.kernel.org # v3.9+ Please don't top-post. I manually fixed it here. > Sorry, I forgot to notice that this specific problem is already fixed in > mmotm with patch "mm: hwpoison: adjust for new thp refcounting", but > considering backporting to -stable, it's easier to handle this separately. > > So Andrew, could you separate out the code of this patch from > "mm: hwpoison: adjust for new thp refcounting"? I don't understand what you're asking for. Please be very specific and carefully identify patches by filename or Subject:. -- 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