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Tue, 26 Aug 2025 06:46:42 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEuxDJCtt4uGtkkNwYc+l5uBaWSrMn5+Sn6RTFNkIfr9/PHfQUvWNUMSRZXgQlOWs52bnkehKXLBXOH5bnIPQs= X-Received: by 2002:a05:6902:1505:b0:e90:11bb:397c with SMTP id 3f1490d57ef6-e951c2e6476mr17866565276.10.1756216001425; Tue, 26 Aug 2025 06:46:41 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250819134205.622806-1-npache@redhat.com> <20250819134205.622806-4-npache@redhat.com> <20250824013746.bvsz3vajjj2kphrl@master> In-Reply-To: <20250824013746.bvsz3vajjj2kphrl@master> From: Nico Pache Date: Tue, 26 Aug 2025 07:46:14 -0600 X-Gm-Features: Ac12FXyLvLHJcV0w6rar3RVrCz2fxN5NrCxMe4grcCkIazMUynhHT0ZTM7eshuk Message-ID: Subject: Re: [PATCH v10 03/13] khugepaged: generalize hugepage_vma_revalidate for mTHP support To: Wei Yang 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, Aug 23, 2025 at 7:37=E2=80=AFPM Wei Yang wrote: > > 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 enable= d. > > > >To ensure madvise_collapse can support working on mTHP orders without th= e > >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 ag= ain"? Good catch, never noticed that. I updated the comment! > > >@@ -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 =3D 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 comme= nt > too. Ack! Thanks for the review! > > >@@ -1134,7 +1135,8 @@ static int collapse_huge_page(struct mm_struct *mm= , unsigned long address, > > goto out_nolock; > > > > mmap_read_lock(mm); > >- result =3D hugepage_vma_revalidate(mm, address, true, &vma, cc); > >+ result =3D hugepage_vma_revalidate(mm, address, true, &vma, cc, > >+ BIT(HPAGE_PMD_ORDER)); > > if (result !=3D 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 =3D hugepage_vma_revalidate(mm, address, true, &vma, cc); > >+ result =3D hugepage_vma_revalidate(mm, address, true, &vma, cc, > >+ BIT(HPAGE_PMD_ORDER)); > > if (result !=3D 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, u= nsigned long start, > > mmap_read_lock(mm); > > mmap_locked =3D true; > > result =3D hugepage_vma_revalidate(mm, addr, fals= e, &vma, > >- cc); > >+ cc, BIT(HPAGE_PM= D_ORDER)); > > if (result !=3D SCAN_SUCCEED) { > > last_fail =3D result; > > goto out_nolock; > >-- > >2.50.1 > > > > -- > Wei Yang > Help you, Help me >