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b=Lkio3xuUd5AU8UgtD6c6jGLmmu91MDtI3qCGmPWKBE6IYaEtIGnF9GHeQHXMlqCJ4 5JvPvUv0EkXz3IFmbmdVFNnQZ25aWUK2JMzsGxmBWYu8nbNku41yXG5xOv8FipfYdD D9pf8Fdw7S4H2c68KzK8dYzavYASaND5XbGPAVhuzklqIhvvilD7IyvfGZZs+B/6HA DZbpId7SXoZMLhYEA6v1og+j2EK3mC089lWwt7szg4fYJSBdpwH4UNaSKnioZ9/7GJ Z9C8RXPS5BOQesIkLOZBUb27B/5L0roWBlWC3kf6XEBsOSgoCMUxgk7MDxmeMC4eiR OMcDZbFBvVylQ== Date: Fri, 5 Jun 2026 18:46:44 +0100 From: Lorenzo Stoakes To: Nico Pache Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, jackmanb@google.com, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, liam@infradead.org, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com Subject: Re: [PATCH mm-unstable v19 10/14] mm/khugepaged: introduce collapse_possible_orders helper functions Message-ID: References: <20260605161422.213817-1-npache@redhat.com> <20260605161422.213817-11-npache@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260605161422.213817-11-npache@redhat.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 6C429180005 X-Stat-Signature: z3afydubh6hdk34f5bs87i6gp43t4s9u X-Rspam-User: X-HE-Tag: 1780681620-172666 X-HE-Meta: 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 q41MoYXA A6tZbwQgeqnBxxdTxYhZ7rFCP3DotikD/E8q213IpTerk26unb1NhY2uReTw4PnuUZjx3uK/v5Z6fSvFxhEO8x1ApGTg3d1L230e10mMaX69gnldHw+VKesPWaKZT0hQUw6rrZoDctEXRq6/ivZRauwXa7y9nN9nluNzSgag/FhlGQEjNRYT9+g9im3fdifrRXEaQxkb+gtL/Cz/kbqMCjJwz25Kyem0TTpryOPQ81KRS0PugxeOIhazxDotsD9KyZhzWx4oLl70jQpsPvZUUydORpRMWtrNU9rO4uvdZkWhB3oesQcvrDxBuetVoWpO86y3Je5zDhWd8zFf+N/DJy2FnjSfCi2DAiw/EcBjyYbInurs7LV9NSXhEqvAdFG7m3ITmb7eCTPDHThUPHXzgrQOHyn6OXlW7OcneW9Y8xm1SzZ1W7uSns2ZLf4naABPGFNI2 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 05, 2026 at 10:14:17AM -0600, Nico Pache wrote: > Add collapse_possible_orders() to generalize THP order eligibility. The > function determines which THP orders are permitted based on collapse > context (khugepaged vs madv_collapse). We also add collapse_possible() > as a thin wrapper around collapse_possible_orders() that returns a bool > rather than the whole bitmap. > > This consolidates collapse configuration logic and provides a clean > interface for future mTHP collapse support where the orders may be > different. > > Acked-by: David Hildenbrand (Arm) > Reviewed-by: Baolin Wang > Signed-off-by: Nico Pache LGTM, so: Reviewed-by: Lorenzo Stoakes > --- > mm/khugepaged.c | 24 +++++++++++++++++++++--- > 1 file changed, 21 insertions(+), 3 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 26c343a6fa3d..ec886a031952 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -554,12 +554,30 @@ void __khugepaged_enter(struct mm_struct *mm) > wake_up_interruptible(&khugepaged_wait); > } > > +/* > + * Check what orders are possible based on the vma and collapse type. > + * This is used to determine if mTHP collapse is a viable option. > + */ > +static unsigned long collapse_possible_orders(struct vm_area_struct *vma, > + vm_flags_t vm_flags, enum tva_type tva_flags) > +{ > + const unsigned long orders = BIT(HPAGE_PMD_ORDER); > + > + return thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); > +} > + > +static bool collapse_possible(struct vm_area_struct *vma, > + vm_flags_t vm_flags, enum tva_type tva_flags) > +{ > + return collapse_possible_orders(vma, vm_flags, tva_flags); > +} > + > void khugepaged_enter_vma(struct vm_area_struct *vma, > vm_flags_t vm_flags) > { > if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && > hugepage_pmd_enabled()) { > - if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) > + if (collapse_possible(vma, vm_flags, TVA_KHUGEPAGED)) > __khugepaged_enter(vma->vm_mm); > } > } > @@ -2700,7 +2718,7 @@ static void collapse_scan_mm_slot(unsigned int progress_max, > cc->progress++; > break; > } > - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { > + if (!collapse_possible(vma, vma->vm_flags, TVA_KHUGEPAGED)) { > cc->progress++; > continue; > } > @@ -3010,7 +3028,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, > BUG_ON(vma->vm_start > start); > BUG_ON(vma->vm_end < end); > > - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_FORCED_COLLAPSE, PMD_ORDER)) > + if (!collapse_possible(vma, vma->vm_flags, TVA_FORCED_COLLAPSE)) > return -EINVAL; > > cc = kmalloc_obj(*cc); > -- > 2.54.0 >