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Sat, 23 Aug 2025 18:37:48 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-61c3174f4d4sm2476072a12.54.2025.08.23.18.37.46 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sat, 23 Aug 2025 18:37:47 -0700 (PDT) Date: Sun, 24 Aug 2025 01:37:46 +0000 From: Wei Yang To: Nico Pache Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com Subject: Re: [PATCH v10 03/13] khugepaged: generalize hugepage_vma_revalidate for mTHP support Message-ID: <20250824013746.bvsz3vajjj2kphrl@master> Reply-To: Wei Yang References: <20250819134205.622806-1-npache@redhat.com> <20250819134205.622806-4-npache@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-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: <20250819134205.622806-4-npache@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) Hi, Nico Some nit below. On Tue, Aug 19, 2025 at 07:41:55AM -0600, Nico Pache wrote: >For khugepaged to support different mTHP orders, we must generalize this >to check if the PMD is not shared by another VMA and the order is enabled. > >To ensure madvise_collapse can support working on mTHP orders without the >PMD order enabled, we need to convert hugepage_vma_revalidate to take a >bitmap of orders. > >No functional change in this patch. > >Reviewed-by: Baolin Wang >Acked-by: David Hildenbrand >Co-developed-by: Dev Jain >Signed-off-by: Dev Jain >Signed-off-by: Nico Pache >--- > mm/khugepaged.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > >diff --git a/mm/khugepaged.c b/mm/khugepaged.c >index b7b98aebb670..2d192ec961d2 100644 >--- a/mm/khugepaged.c >+++ b/mm/khugepaged.c There is a comment above this function, which says "revalidate vma before taking mmap_lock". I am afraid it is "after taking mmap_lock"? or "after taking mmap_lock again"? >@@ -917,7 +917,7 @@ static int collapse_find_target_node(struct collapse_control *cc) > static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > bool expect_anon, > struct vm_area_struct **vmap, >- struct collapse_control *cc) >+ struct collapse_control *cc, unsigned long orders) > { > struct vm_area_struct *vma; > enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED : >@@ -930,9 +930,10 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > if (!vma) > return SCAN_VMA_NULL; > >+ /* Always check the PMD order to insure its not shared by another VMA */ > if (!thp_vma_suitable_order(vma, address, PMD_ORDER)) > return SCAN_ADDRESS_RANGE; >- if (!thp_vma_allowable_order(vma, vma->vm_flags, type, PMD_ORDER)) >+ if (!thp_vma_allowable_orders(vma, vma->vm_flags, type, orders)) > return SCAN_VMA_CHECK; > /* > * Anon VMA expected, the address may be unmapped then Below is a comment, "thp_vma_allowable_order may return". Since you use thp_vma_allowable_orders, maybe we need to change the comment too. >@@ -1134,7 +1135,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > goto out_nolock; > > mmap_read_lock(mm); >- result = hugepage_vma_revalidate(mm, address, true, &vma, cc); >+ result = hugepage_vma_revalidate(mm, address, true, &vma, cc, >+ BIT(HPAGE_PMD_ORDER)); > if (result != SCAN_SUCCEED) { > mmap_read_unlock(mm); > goto out_nolock; >@@ -1168,7 +1170,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > * mmap_lock. > */ > mmap_write_lock(mm); >- result = hugepage_vma_revalidate(mm, address, true, &vma, cc); >+ result = hugepage_vma_revalidate(mm, address, true, &vma, cc, >+ BIT(HPAGE_PMD_ORDER)); > if (result != SCAN_SUCCEED) > goto out_up_write; > /* check if the pmd is still valid */ >@@ -2807,7 +2810,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, > mmap_read_lock(mm); > mmap_locked = true; > result = hugepage_vma_revalidate(mm, addr, false, &vma, >- cc); >+ cc, BIT(HPAGE_PMD_ORDER)); > if (result != SCAN_SUCCEED) { > last_fail = result; > goto out_nolock; >-- >2.50.1 > -- Wei Yang Help you, Help me