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Shutemov" To: Vlastimil Babka Cc: Qian Cai , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, "Kirill A. Shutemov" , Matthew Wilcox , Mel Gorman , Michal Hocko , Dmitry Vyukov , Walter Wu , Andrey Ryabinin Subject: Re: [PATCH v2 2/3] mm, page_owner: decouple freeing stack trace from debug_pagealloc Message-ID: <20191001113505.kidbhjl7u2hawxvb@box> References: <20190930122916.14969-1-vbabka@suse.cz> <20190930122916.14969-3-vbabka@suse.cz> <1569847787.5576.244.camel@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Sep 30, 2019 at 11:39:34PM +0200, Vlastimil Babka wrote: > On 9/30/19 2:49 PM, Qian Cai wrote: > >> --- a/Documentation/admin-guide/kernel-parameters.txt > >> +++ b/Documentation/admin-guide/kernel-parameters.txt > >> @@ -3237,6 +3237,14 @@ > >> we can turn it on. > >> on: enable the feature > >> > >> + page_owner_free= > >> + [KNL] When enabled together with page_owner, store also > >> + the stack of who frees a page, for error page dump > >> + purposes. This is also implicitly enabled by > >> + debug_pagealloc=on or KASAN, so only page_owner=on is > >> + sufficient in those cases. > >> + on: enable the feature > >> + > > > > If users are willing to set page_owner=on, what prevent them from enabling KASAN > > as well? That way, we don't need this additional parameter. > > Well, my use case is shipping production kernels with CONFIG_PAGE_OWNER > and CONFIG_DEBUG_PAGEALLOC enabled, and instructing users to boot-time > enable only for troubleshooting a crash or memory leak, without a need > to install a debug kernel. Things like static keys and page_ext > allocations makes this possible without CPU and memory overhead when not > boot-time enabled. I don't know too much about KASAN internals, but I > assume it's not possible to use it that way on production kernels yet? I don't know about production, but QEMU (without KVM acceleration) is painfully slow if KASAN is enabled. -- Kirill A. Shutemov