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bh=hM0bwcDvgkAIjvvxpcJVRLkstfxzoDyPt2D7iUnvNG4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fv32pv5Dou8qrSImdDNerwO5oykE51gQE6kk7ssw+dRnxB/fixTTy1oEQfGBMBcoI Pn9zy+xWWwvifEgqyoZdHHSZcILSKaEP9D/7qfcV+NdBU56EErN5+96HxSehklD/DM N17tP9ng9rOp2F5TF7dZuBSAYEY+n/qa6Ef4RL6k= Date: Wed, 12 Apr 2023 13:33:31 -0700 From: Andrew Morton To: Alexander Potapenko Cc: urezki@gmail.com, hch@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, elver@google.com, dvyukov@google.com, kasan-dev@googlegroups.com, Dipanjan Das Subject: Re: [PATCH 2/2] mm: kmsan: handle alloc failures in kmsan_ioremap_page_range() Message-Id: <20230412133331.e26920856ccf94edd057c1e0@linux-foundation.org> In-Reply-To: <20230412145300.3651840-2-glider@google.com> References: <20230412145300.3651840-1-glider@google.com> <20230412145300.3651840-2-glider@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 727BF1A0017 X-Stat-Signature: 7radmw1idcmojjdd7fibkpt8garosdae X-Rspam-User: X-HE-Tag: 1681331614-58828 X-HE-Meta: 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 Emsj8/YE 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 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 Wed, 12 Apr 2023 16:53:00 +0200 Alexander Potapenko wrote: > Similarly to kmsan_vmap_pages_range_noflush(), > kmsan_ioremap_page_range() must also properly handle allocation/mapping > failures. In the case of such, it must clean up the already created > metadata mappings and return an error code, so that the failure can be > propagated to ioremap_page_range(). Unlike [1/2], this changelog doesn't describe the user-visible effects. A bit of clicking takes me to : kmsan's allocation of shadow or origin memory in : kmsan_vmap_pages_range_noflush() fails silently due to fault injection : (FI). KMSAN sort of "swallows" the allocation failure, and moves on. : When either of them is later accessed while updating the metadata, : there are no checks to test the validity of the respective pointers, : which results in a page fault. So I'll add that to the changelog and shall add cc:stable to both patches.