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Tue, 12 May 2026 09:00:59 +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 KLVdGkvsAmrfHAAAD6G6ig (envelope-from ); Tue, 12 May 2026 09:00:59 +0000 Date: Tue, 12 May 2026 11:00:53 +0200 From: Oscar Salvador To: ackerleytng@google.com Cc: Muchun Song , David Hildenbrand , Andrew Morton , fvdl@google.com, jiaqiyan@google.com, joshua.hahnjy@gmail.com, jthoughton@google.com, mhocko@kernel.org, michael.roth@amd.com, pasha.tatashin@soleen.com, pbonzini@redhat.com, peterx@redhat.com, pratyush@kernel.org, rick.p.edgecombe@intel.com, rientjes@google.com, roman.gushchin@linux.dev, seanjc@google.com, shakeel.butt@linux.dev, shivankg@amd.com, vannapurve@google.com, yan.y.zhao@intel.com, Dan Williams , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/6] mm: hugetlb: Consolidate interpretation of gbl_chg within alloc_hugetlb_folio() Message-ID: References: <20260506-hugetlb-open-up-v2-0-826a0c5f28fc@google.com> <20260506-hugetlb-open-up-v2-1-826a0c5f28fc@google.com> 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: <20260506-hugetlb-open-up-v2-1-826a0c5f28fc@google.com> X-Spam-Level: X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[26]; MISSING_XM_UA(0.00)[]; ARC_NA(0.00)[]; TAGGED_RCPT(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_DN_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,kernel.org,linux-foundation.org,google.com,gmail.com,amd.com,soleen.com,redhat.com,intel.com,ziepe.ca,kvack.org,vger.kernel.org]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,imap1.dmz-prg2.suse.org:helo,localhost.localdomain:mid] X-Spam-Flag: NO X-Spam-Score: -2.80 On Wed, May 06, 2026 at 08:54:37AM -0700, Ackerley Tng via B4 Relay wrote: > From: Ackerley Tng > > The dequeue_hugetlb_folio_vma() function currently handles the gbl_chg > parameter to determine if a folio can be dequeued based on global page > availability. This leaks reservation-specific logic into the dequeueing > path. > > Relocate this logic to alloc_hugetlb_folio() so that > dequeue_hugetlb_folio_vma() focuses solely on selecting and dequeuing a > folio. In alloc_hugetlb_folio(), only attempt to dequeue a folio if a > reservation exists (gbl_chg == 0) or if there are available huge pages in > the global pool. > > No functional change intended. > > Signed-off-by: Ackerley Tng > Reviewed-by: James Houghton Acked-by: Oscar Salvador I am ok with this but: > --- > mm/hugetlb.c | 24 +++++++++--------------- > 1 file changed, 9 insertions(+), 15 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f24bf49be047e..8be246b4e6134 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c ... > @@ -2939,12 +2929,16 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, > goto out_uncharge_cgroup_reservation; > > spin_lock_irq(&hugetlb_lock); > + > /* > - * glb_chg is passed to indicate whether or not a page must be taken > - * from the global free pool (global change). gbl_chg == 0 indicates > - * a reservation exists for the allocation. > + * gbl_chg == 0 indicates a reservation exists for the allocation - so > + * try dequeuing a page. If there are available_huge_pages(), try using > + * them! This comment is a bit obfuscated. I miss "in case there is no reservation, check whether we have available pages in the pool to satisfy the request" or something like that. -- Oscar Salvador SUSE Labs