From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id D269A6B0003 for ; Wed, 25 Apr 2018 16:20:52 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id b2so11524589pgt.6 for ; Wed, 25 Apr 2018 13:20:52 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id d14si15126141pfl.122.2018.04.25.13.20.50 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 25 Apr 2018 13:20:50 -0700 (PDT) Subject: Re: [PATCH v4] fault-injection: introduce kvmalloc fallback options References: <20180421144757.GC14610@bombadil.infradead.org> <20180423151545.GU17484@dhcp22.suse.cz> <20180424125121.GA17484@dhcp22.suse.cz> <20180424162906.GM17484@dhcp22.suse.cz> <20180424170349.GQ17484@dhcp22.suse.cz> <20180424173836.GR17484@dhcp22.suse.cz> From: Randy Dunlap Message-ID: <1114eda5-9b1f-4db8-2090-556b4a37c532@infradead.org> Date: Wed, 25 Apr 2018 13:20:39 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mikulas Patocka , Michal Hocko Cc: Matthew Wilcox , David Miller , Andrew Morton , linux-mm@kvack.org, eric.dumazet@gmail.com, edumazet@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, dm-devel@redhat.com, Vlastimil Babka On 04/25/2018 01:02 PM, Mikulas Patocka wrote: > > > From: Mikulas Patocka > Subject: [PATCH v4] fault-injection: introduce kvmalloc fallback options > > This patch introduces a fault-injection option "kvmalloc_fallback". This > option makes kvmalloc randomly fall back to vmalloc. > > Unfortunatelly, some kernel code has bugs - it uses kvmalloc and then Unfortunately, > uses DMA-API on the returned memory or frees it with kfree. Such bugs were > found in the virtio-net driver, dm-integrity or RHEL7 powerpc-specific > code. This options helps to test for these bugs. > > The patch introduces a config option FAIL_KVMALLOC_FALLBACK_PROBABILITY. > It can be enabled in distribution debug kernels, so that kvmalloc abuse > can be tested by the users. The default can be overriden with overridden > "kvmalloc_fallback" parameter or in /sys/kernel/debug/kvmalloc_fallback/. > > Signed-off-by: Mikulas Patocka > > --- > Documentation/fault-injection/fault-injection.txt | 7 +++++ > include/linux/fault-inject.h | 9 +++--- > kernel/futex.c | 2 - > lib/Kconfig.debug | 15 +++++++++++ > mm/failslab.c | 2 - > mm/page_alloc.c | 2 - > mm/util.c | 30 ++++++++++++++++++++++ > 7 files changed, 60 insertions(+), 7 deletions(-) > > Index: linux-2.6/Documentation/fault-injection/fault-injection.txt > =================================================================== > --- linux-2.6.orig/Documentation/fault-injection/fault-injection.txt 2018-04-16 21:08:34.000000000 +0200 > +++ linux-2.6/Documentation/fault-injection/fault-injection.txt 2018-04-25 21:36:36.000000000 +0200 > @@ -15,6 +15,12 @@ o fail_page_alloc > > injects page allocation failures. (alloc_pages(), get_free_pages(), ...) > > +o kvmalloc_faillback kvmalloc_fallback > + > + makes the function kvmalloc randonly fall back to vmalloc. This could be used randomly > + to detects bugs such as using DMA-API on the result of kvmalloc or freeing > + the result of kvmalloc with free. > + > o fail_futex > > injects futex deadlock and uaddr fault errors. > @@ -167,6 +173,7 @@ use the boot option: > > failslab= > fail_page_alloc= > + kvmalloc_faillback= kvmalloc_fallback= > fail_make_request= > fail_futex= > mmc_core.fail_request=,,, > Index: linux-2.6/lib/Kconfig.debug > =================================================================== > --- linux-2.6.orig/lib/Kconfig.debug 2018-04-25 15:56:16.000000000 +0200 > +++ linux-2.6/lib/Kconfig.debug 2018-04-25 21:39:45.000000000 +0200 > @@ -1527,6 +1527,21 @@ config FAIL_PAGE_ALLOC > help > Provide fault-injection capability for alloc_pages(). > > +config FAIL_KVMALLOC_FALLBACK_PROBABILITY > + int "Default kvmalloc fallback probability" > + depends on FAULT_INJECTION > + range 0 100 > + default "0" > + help > + This option will make kvmalloc randomly fall back to vmalloc. > + Normally, kvmalloc falls back to vmalloc only rarely, if memory > + is fragmented. > + > + This option helps to detect hard-to-reproduce driver bugs, for > + example using DMA API on the result of kvmalloc. > + > + The default may be overriden with the kvmalloc_faillback parameter. overridden kvmalloc_fallback > + > config FAIL_MAKE_REQUEST > bool "Fault-injection capability for disk IO" > depends on FAULT_INJECTION && BLOCK -- ~Randy