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Thu, 08 Aug 2024 10:18:17 -0700 (PDT) Received: from fan ([2601:646:8f03:9fee:1fa7:f643:a5d2:2c9c]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff59295294sm127164895ad.253.2024.08.08.10.18.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Aug 2024 10:18:17 -0700 (PDT) From: Fan Ni X-Google-Original-From: Fan Ni Date: Thu, 8 Aug 2024 10:17:59 -0700 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, yosryahmed@google.com Subject: Re: [PATCH v3 1/4] mm: update the memmap stat before page is freed Message-ID: References: <20240808154237.220029-1-pasha.tatashin@soleen.com> <20240808154237.220029-2-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-cxl@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: <20240808154237.220029-2-pasha.tatashin@soleen.com> On Thu, Aug 08, 2024 at 03:42:34PM +0000, Pasha Tatashin wrote: > It is more logical to update the stat before the page is freed, to avoid > use after free scenarios. > > Fixes: 15995a352474 ("mm: report per-page metadata information") > Signed-off-by: Pasha Tatashin > Reviewed-by: David Hildenbrand Reviewed-by: Fan Ni > --- > 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 start, 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 = vmalloc_to_page(addr); > pgdat = page_pgdat(page); > + mod_node_page_state(pgdat, NR_MEMMAP, > + -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE))); > vfree(addr); > } else { > page = virt_to_page(addr); > pgdat = page_pgdat(page); > + mod_node_page_state(pgdat, NR_MEMMAP, > + -1L * (DIV_ROUND_UP(table_size, PAGE_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 >