From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH v3] kvmalloc: always use vmalloc if CONFIG_DEBUG_SG Date: Tue, 24 Apr 2018 06:51:21 -0600 Message-ID: <20180424125121.GA17484@dhcp22.suse.cz> References: <20180420130852.GC16083@dhcp22.suse.cz> <20180420210200.GH10788@bombadil.infradead.org> <20180421144757.GC14610@bombadil.infradead.org> <20180423151545.GU17484@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Mikulas Patocka Cc: dm-devel@redhat.com, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox , virtualization@lists.linux-foundation.org, linux-mm@kvack.org, edumazet@google.com, Andrew Morton , David Miller , Vlastimil Babka List-Id: dm-devel.ids On Mon 23-04-18 20:06:16, Mikulas Patocka wrote: [...] > @@ -404,6 +405,12 @@ void *kvmalloc_node(size_t size, gfp_t f > */ > WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL); > > +#ifdef CONFIG_DEBUG_SG > + /* Catch bugs when the caller uses DMA API on the result of kvmalloc. */ > + if (!(prandom_u32_max(2) & 1)) > + goto do_vmalloc; > +#endif I really do not think there is anything DEBUG_SG specific here. Why you simply do not follow should_failslab path or even reuse the function? > + > /* > * We want to attempt a large physically contiguous block first because > * it is less likely to fragment multiple larger blocks and therefore > @@ -427,6 +434,9 @@ void *kvmalloc_node(size_t size, gfp_t f > if (ret || size <= PAGE_SIZE) > return ret; > > +#ifdef CONFIG_DEBUG_SG > +do_vmalloc: > +#endif > return __vmalloc_node_flags_caller(size, node, flags, > __builtin_return_address(0)); > } -- Michal Hocko SUSE Labs