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Tue, 14 May 2024 21:03:44 +0000 Date: Tue, 14 May 2024 23:03:39 +0200 From: Oscar Salvador To: =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= Subject: Re: [PATCH v2 5/8] riscv: mm: Take memory hotplug read-lock during kernel page table dump Message-ID: References: <20240514140446.538622-1-bjorn@kernel.org> <20240514140446.538622-6-bjorn@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240514140446.538622-6-bjorn@kernel.org> X-Rspamd-Action: no action X-Rspamd-Queue-Id: 9CA9A1FBA6 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-6.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; DWL_DNSWL_MED(-2.00)[suse.de:dkim]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCPT_COUNT_TWELVE(0.00)[17]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_CC(0.00)[rivosinc.com,eecs.berkeley.edu,redhat.com,dabbelt.com,sifive.com,lists.infradead.org,catalinasystems.io,gmail.com,ventanamicro.com,vger.kernel.org,kvack.org,lists.linux-foundation.org]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[rivosinc.com:email,suse.de:dkim,suse.de:email] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240514_140347_796163_A3C7D094 X-CRM114-Status: GOOD ( 11.88 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Alexandre Ghiti , Chethan Seshadri , David Hildenbrand , linux-kernel@vger.kernel.org, Andrew Bresticker , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Santosh Mamila , linux-mm@kvack.org, Sivakumar Munnangi , Palmer Dabbelt , Paul Walmsley , linux-riscv@lists.infradead.org, virtualization@lists.linux-foundation.org, Lorenzo Stoakes Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Tue, May 14, 2024 at 04:04:43PM +0200, Bj=F6rn T=F6pel wrote: > From: Bj=F6rn T=F6pel > = > During memory hot remove, the ptdump functionality can end up touching > stale data. Avoid any potential crashes (or worse), by holding the > memory hotplug read-lock while traversing the page table. > = > This change is analogous to arm64's commit bf2b59f60ee1 ("arm64/mm: > Hold memory hotplug lock while walking for kernel page table dump"). > = > Signed-off-by: Bj=F6rn T=F6pel Reviewed-by: Oscar Salvador funny enough, it seems arm64 and riscv are the only ones holding the hotplug lock here. I think we have the same problem on the other arches as well (at least on x86_64 that I can see). If we happen to finally need the lock in those, I would rather have a centric function in the generic mm code with the locking and then calling an arch specific ptdump_show function, so the lock is not scattered. But that is another story. = -- = Oscar Salvador SUSE Labs _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv