From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id DFBC16B0038 for ; Fri, 24 Feb 2017 21:28:47 -0500 (EST) Received: by mail-pf0-f198.google.com with SMTP id r67so55914738pfr.6 for ; Fri, 24 Feb 2017 18:28:47 -0800 (PST) Received: from dggrg02-dlp.huawei.com ([45.249.212.188]) by mx.google.com with ESMTPS id k184si480623pgd.247.2017.02.24.18.28.46 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 24 Feb 2017 18:28:46 -0800 (PST) Subject: Re: Is MADV_HWPOISON supposed to work only on faulted-in pages? References: <6a445beb-119c-9a9a-0277-07866afe4924@redhat.com> <20170220050016.GA15533@hori1.linux.bs1.fc.nec.co.jp> <20170223032342.GA18740@hori1.linux.bs1.fc.nec.co.jp> From: Yisheng Xie Message-ID: <1ba376aa-5e7c-915f-35d1-2d4eef0cad88@huawei.com> Date: Sat, 25 Feb 2017 10:28:15 +0800 MIME-Version: 1.0 In-Reply-To: <20170223032342.GA18740@hori1.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi , Jan Stancek Cc: "linux-mm@kvack.org" , "ltp@lists.linux.it" hi Naoya, On 2017/2/23 11:23, Naoya Horiguchi wrote: > On Mon, Feb 20, 2017 at 05:00:17AM +0000, Horiguchi Naoya($BKY8}(B $BD>Li(B) wrote: >> On Tue, Feb 14, 2017 at 04:41:29PM +0100, Jan Stancek wrote: >>> Hi, >>> >>> code below (and LTP madvise07 [1]) doesn't produce SIGBUS, >>> unless I touch/prefault page before call to madvise(). >>> >>> Is this expected behavior? >> >> Thank you for reporting. >> >> madvise(MADV_HWPOISON) triggers page fault when called on the address >> over which no page is faulted-in, so I think that SIGBUS should be >> called in such case. >> >> But it seems that memory error handler considers such a page as "reserved >> kernel page" and recovery action fails (see below.) >> >> [ 383.371372] Injecting memory failure for page 0x1f10 at 0x7efcdc569000 >> [ 383.375678] Memory failure: 0x1f10: reserved kernel page still referenced by 1 users >> [ 383.377570] Memory failure: 0x1f10: recovery action for reserved kernel page: Failed >> >> I'm not sure how/when this behavior was introduced, so I try to understand. > > I found that this is a zero page, which is not recoverable for memory > error now. > >> IMO, the test code below looks valid to me, so no need to change. > > I think that what the testcase effectively does is to test whether memory > handling on zero pages works or not. > And the testcase's failure seems acceptable, because it's simply not-implemented yet. > Maybe recovering from error on zero page is possible (because there's no data > loss for memory error,) but I'm not sure that code might be simple enough and/or > it's worth doing ... I question about it, if a memory error happened on zero page, it will cause all of data read from zero page is error, I mean no-zero, right? And can we just use re-initial it with zero data maybe by memset ? Thanks Yisheng Xie. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yisheng Xie Date: Sat, 25 Feb 2017 10:28:15 +0800 Subject: [LTP] Is MADV_HWPOISON supposed to work only on faulted-in pages? In-Reply-To: <20170223032342.GA18740@hori1.linux.bs1.fc.nec.co.jp> References: <6a445beb-119c-9a9a-0277-07866afe4924@redhat.com> <20170220050016.GA15533@hori1.linux.bs1.fc.nec.co.jp> <20170223032342.GA18740@hori1.linux.bs1.fc.nec.co.jp> Message-ID: <1ba376aa-5e7c-915f-35d1-2d4eef0cad88@huawei.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: ltp@lists.linux.it hi Naoya, On 2017/2/23 11:23, Naoya Horiguchi wrote: > On Mon, Feb 20, 2017 at 05:00:17AM +0000, Horiguchi Naoya(堀口直也) wrote: >> On Tue, Feb 14, 2017 at 04:41:29PM +0100, Jan Stancek wrote: >>> Hi, >>> >>> code below (and LTP madvise07 [1]) doesn't produce SIGBUS, >>> unless I touch/prefault page before call to madvise(). >>> >>> Is this expected behavior? >> >> Thank you for reporting. >> >> madvise(MADV_HWPOISON) triggers page fault when called on the address >> over which no page is faulted-in, so I think that SIGBUS should be >> called in such case. >> >> But it seems that memory error handler considers such a page as "reserved >> kernel page" and recovery action fails (see below.) >> >> [ 383.371372] Injecting memory failure for page 0x1f10 at 0x7efcdc569000 >> [ 383.375678] Memory failure: 0x1f10: reserved kernel page still referenced by 1 users >> [ 383.377570] Memory failure: 0x1f10: recovery action for reserved kernel page: Failed >> >> I'm not sure how/when this behavior was introduced, so I try to understand. > > I found that this is a zero page, which is not recoverable for memory > error now. > >> IMO, the test code below looks valid to me, so no need to change. > > I think that what the testcase effectively does is to test whether memory > handling on zero pages works or not. > And the testcase's failure seems acceptable, because it's simply not-implemented yet. > Maybe recovering from error on zero page is possible (because there's no data > loss for memory error,) but I'm not sure that code might be simple enough and/or > it's worth doing ... I question about it, if a memory error happened on zero page, it will cause all of data read from zero page is error, I mean no-zero, right? And can we just use re-initial it with zero data maybe by memset ? Thanks Yisheng Xie.