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AJvYcCWYNjstZZR3M4qX5Y7YYJJw4J8t1lf43QBVO1D/pokgZMx+hBaXJHECdIFH615g2kgtWwXszRennmvhHlG98pkdQAE= X-Gm-Message-State: AOJu0Yw3pWwibzwlgK2/1j4lYuDcObhTJ7n1v+XGVaW8HsWIP1bOWVez ZOAtVp0+ph5yq1sxtVaRZmQXV/1LoFo0QpP0jQcjtCKzCcIAZSX+PsqJADWT/oRt+kr3N68PDSV Re8uWLLb8SL8e81nDvcLr85WtvMkZXyuMEFa4 X-Google-Smtp-Source: AGHT+IFL88mjWQ2Zggrwbd607XFMRGP1XRGTL3dSoaDAXad6oVRymc9qOzsbgGNM2EuGuB6XKcuRs75CW9Ih+Pzinbg= X-Received: by 2002:a05:6359:4c91:b0:1ac:f668:9920 with SMTP id e5c5f4694b2df-1b15cfe3845mr285813155d.19.1723137695238; Thu, 08 Aug 2024 10:21:35 -0700 (PDT) MIME-Version: 1.0 References: <20240808154237.220029-1-pasha.tatashin@soleen.com> <20240808154237.220029-2-pasha.tatashin@soleen.com> In-Reply-To: From: Yosry Ahmed Date: Thu, 8 Aug 2024 10:20:54 -0700 Message-ID: Subject: Re: [PATCH v3 1/4] mm: update the memmap stat before page is freed To: Pasha Tatashin Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, cerasuolodomenico@gmail.com, hannes@cmpxchg.org, j.granados@samsung.com, lizhijian@fujitsu.com, muchun.song@linux.dev, nphamcs@gmail.com, rientjes@google.com, rppt@kernel.org, souravpanda@google.com, vbabka@suse.cz, willy@infradead.org, dan.j.williams@intel.com, yi.zhang@redhat.com, alison.schofield@intel.com, david@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 969ABC0018 X-Rspamd-Server: rspam01 X-Stat-Signature: chkicwnecdxrpim54rdg9n3zsga7we76 X-HE-Tag: 1723137696-428166 X-HE-Meta: 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 Vl+BEdby znVXCUC8wx6KrIkmQQOvHm5iOkWazUG7BcStyDyhaG8SIpXTPHD/NB9Y6SFsiBbnRT9usaKdsDf0/wtJMlY52Z6rd0L7wV3WS/T7QRvDe1JcI+VxtCl4s8AANG+yIhFpwjuHwzgiSFJsk2jXYApRvXryK9GrXHMRiRXvhiKE+IbFG8bm69DMNL+t43R7PLvSAQEq4riIxLP55IfTUQx2Ig5+t1RbHQbu/TI3G/9o4ljRr833/U3Uu5qSjviUrgZIVcL2QXn3ppBTVGXWdZol86UhnAQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 8, 2024 at 10:17=E2=80=AFAM Yosry Ahmed = wrote: > > On Thu, Aug 8, 2024 at 8:42=E2=80=AFAM Pasha Tatashin wrote: > > > > It is more logical to update the stat before the page is freed, to avoi= d > > use after free scenarios. > > > > Fixes: 15995a352474 ("mm: report per-page metadata information") > > Signed-off-by: Pasha Tatashin > > Reviewed-by: David Hildenbrand > > Reviewed-by: Yosry Ahmed Actually although I think this patch is correct, it shouldn't be needed after patch 4 because we no longer use the page or pgdat to update the stats. > > > --- > > mm/hugetlb_vmemmap.c | 4 ++-- > > mm/page_ext.c | 8 ++++---- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > > index 829112b0a914..fa83a7b38199 100644 > > --- a/mm/hugetlb_vmemmap.c > > +++ b/mm/hugetlb_vmemmap.c > > @@ -185,11 +185,11 @@ static int vmemmap_remap_range(unsigned long star= t, unsigned long end, > > static inline void free_vmemmap_page(struct page *page) > > { > > if (PageReserved(page)) { > > - free_bootmem_page(page); > > mod_node_page_state(page_pgdat(page), NR_MEMMAP_BOOT, -= 1); > > + free_bootmem_page(page); > > } else { > > - __free_page(page); > > mod_node_page_state(page_pgdat(page), NR_MEMMAP, -1); > > + __free_page(page); > > } > > } > > > > diff --git a/mm/page_ext.c b/mm/page_ext.c > > index c191e490c401..962d45eee1f8 100644 > > --- a/mm/page_ext.c > > +++ b/mm/page_ext.c > > @@ -330,18 +330,18 @@ static void free_page_ext(void *addr) > > if (is_vmalloc_addr(addr)) { > > page =3D vmalloc_to_page(addr); > > pgdat =3D page_pgdat(page); > > + mod_node_page_state(pgdat, NR_MEMMAP, > > + -1L * (DIV_ROUND_UP(table_size, PAG= E_SIZE))); > > vfree(addr); > > } else { > > page =3D virt_to_page(addr); > > pgdat =3D page_pgdat(page); > > + mod_node_page_state(pgdat, NR_MEMMAP, > > + -1L * (DIV_ROUND_UP(table_size, PAG= E_SIZE))); > > BUG_ON(PageReserved(page)); > > kmemleak_free(addr); > > free_pages_exact(addr, table_size); > > } > > - > > - mod_node_page_state(pgdat, NR_MEMMAP, > > - -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE))= ); > > - > > } > > > > static void __free_page_ext(unsigned long pfn) > > -- > > 2.46.0.76.ge559c4bf1a-goog > >