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Wed, 12 Aug 2026 09:36:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id WWtUNI4+fGoKAwAAD6G6ig (envelope-from ); Wed, 12 Aug 2026 09:36:14 +0000 Date: Wed, 12 Aug 2026 10:36:13 +0100 From: Pedro Falcato To: "Nico Pache (Red Hat)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan Subject: Re: [PATCH v4 3/7] mm/khugepaged: introduce a count_collapse_event() helper Message-ID: References: <20260811-khugepaged_pte_refactor-v4-0-ddac39d61c4a@linux.dev> <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> X-Spam-Score: -4.01 X-Spam-Level: X-Rspamd-Action: no action X-Rspamd-Queue-Id: 42BB23E50 X-Spamd-Result: default: False [-4.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[21]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim,alibaba.com:email,linux.dev:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO On Tue, Aug 11, 2026 at 06:48:35AM -0600, Nico Pache (Red Hat) wrote: > Provide a simple helper function to help reduce a often used, and > duplicate pattern across the khugepaged code. > > When collapsing to a PMD we need to record a vm_event and the mTHP_stat > event. When doing mTHP collapse we only update the mTHP stat. > > Reviewed-by: Baolin Wang > Acked-by: David Hildenbrand (Arm) > Acked-by: Usama Arif > Signed-off-by: Nico Pache (Red Hat) > --- > mm/khugepaged.c | 42 +++++++++++++++++++++--------------------- > 1 file changed, 21 insertions(+), 21 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 8babd4c97db6..cae510aa2914 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -688,6 +688,14 @@ static inline bool folio_pte_referenced(struct folio *folio, > return pte_young(pteval) || mmu_notifier_test_young(vma->vm_mm, addr); > } > > +static void count_collapse_event(unsigned int order, enum vm_event_item vm_event, > + enum mthp_stat_item mthp_event) > +{ > + if (is_pmd_order(order)) > + count_vm_event(vm_event); > + count_mthp_stat(order, mthp_event); Maintaining two counters for the same thing is Peak Tech Debt. Would it be somehow possible to redirect /proc/vmstat to PMD_ORDER mTHP stats? > +} > + > static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > unsigned long start_addr, pte_t *pte, struct collapse_control *cc, > unsigned int order, struct list_head *compound_pagelist) > @@ -708,9 +716,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > if (pte_none_or_zero(pteval)) { > if (++none_or_zero > max_ptes_none) { > result = SCAN_EXCEED_NONE_PTE; > - if (is_pmd_order(order)) > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE); > + count_collapse_event(order, THP_SCAN_EXCEED_NONE_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_NONE); This is nicer than open coding the add, though. One step at a time :) Reviewed-by: Pedro Falcato -- Pedro