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Wed, 04 Nov 2026 07:46:19 +0000 X-Mizu-Trace-ID: ee7e5ef34284ef57 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: ljs@kernel.org Cc: david@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, kas@kernel.org, akpm@linux-foundation.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun@kernel.org, longman@redhat.com, surenb@google.com, vbabka@kernel.org, shakeel.butt@linux.dev, yonghong.song@linux.dev, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH 1/5] Revert "mm/khugepaged: remove definition of struct khugepaged_mm_slot" Date: Wed, 4 Nov 2026 15:46:13 +0800 Message-ID: <20261104074613.30583-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261103-khugepaged-latency-fix-v1-1-a07ab16ac860@kernel.org> References: <20261103-khugepaged-latency-fix-v1-1-a07ab16ac860@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 53E96A0007 X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: 3gr1hem1z3d59q5mejtko6z996waf69s X-HE-Tag: 1793778383-885585 X-HE-Meta: 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 DIaWsIHc 6bfGAiMHsZhuAJCWOKm582ZHM3P+rM37OxLVF9yBPcVrMywfe65jlkj+tYgr+zYp6uAc6OxGexLbKzSzbw6LMNR07dIIgD/x2h+GP+ajuVkKBGjkjKKkR7M07nRWqlrMoNrDwuwQjvO3dzrbKMVKyR0fFMTIA2Aukx9Gv6K21ShAnzADKnpVw3wafs4hLlDkdR/sZdES+DbbmtxP+nGAKki7hfgo+xRp5bf6p1oLxlFoNQive0WdxLyZo7vMRMfzPUKcfnq7xzzi68pSKRvQffMcGttRCRwNeH7g/gEcw3YCOLfYfNnojnIXjzQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 03, 2026 at 08:27:42AM +0000, Lorenzo Stoakes (ARM) wrote: >This partially reverts commit b4c9ffb54b32 ("mm/khugepaged: remove >definition of struct khugepaged_mm_slot"), as a subsequent commit needs to >resurrect this type to store additional data alongside the mm_slot. > >The stated intent of the commit was to address a NULL check in >__khugepaged_exit(): > > mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot); > >slot can be NULL and mm_slot_entry() is an alias for container_of(), so >this is container_of() a NULL value. > >This was benign as there was only 1 field in khugepaged_mm_slot (offsetting >NULL at 0 results in NULL), however it was right to fix this, so retain the >fix. > >It also unwrapped KMEM_CACHE() in khugepaged_init(). This was a mistake, >and was itself reverted in commit c14bdcc9f274 ("mm/khugepaged: use >KMEM_CACHE()"). Therefore, retain the KMEM_CACHE() form in this revert. > >Signed-off-by: Lorenzo Stoakes (ARM) >--- With patch #02 adding a per-mm scan position, bringing khugepaged_mm_slot back looks reasonable to me ;) Reviewed-by: Lance Yang