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AJvYcCV02EKFM3bc3+TdYQDi+eaRcUW96hehK0V8P78jTRhV8My81Ry5n6lj5A7HNhT95rWkiPb84Fy5@vger.kernel.org X-Gm-Message-State: AOJu0YzpHQkUlhoCoTPONpZgssIqvxq9nQaq0sMQQearFE0nChqHOWP5 oMP9ioi8LNNnmh76lh0FPAqmro5It3D/jDBkBXgbqXFKLCObpnkDm2bgfKdpTCw= X-Gm-Gg: ASbGncuqHzSPD68/YFYibHCIQNDEANGN6QnU1ZEtbXi8cyTLJzzZZ3IROginsCW0U/t 1V0oMGZs2ywxudOaBpzSLspkCQrWeyeuYwJsOzaW3y5XtRYyJfBds1thHwe6gm5mEPlxxtK3xTZ CRB61k7VV4P+pvjFzTzU21H5sYpakpXcSKksMECGV2AjQEYw1PvPWjww3jjCA6qq0ka/ub8NtKb Mc86ZnD3fAHiNr9iBrTGmUVpj1D93XNt0BlVk1OI/2FX3A= X-Google-Smtp-Source: AGHT+IG4/pMDJNly6UpcXjj9YqlCTPXUKoKZr4j95kG0fcImiNV2JPjd07+8pLaKIe3xJptBa0NikQ== X-Received: by 2002:a05:6000:410f:b0:385:f2a2:50df with SMTP id ffacd0b85a97d-3864cea200amr4204805f8f.27.1734006396535; Thu, 12 Dec 2024 04:26:36 -0800 (PST) Received: from localhost ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4362559ed8dsm15780115e9.23.2024.12.12.04.26.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Dec 2024 04:26:36 -0800 (PST) Date: Thu, 12 Dec 2024 13:26:35 +0100 From: Michal Hocko To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , Christoph Hellwig , linux-mm@kvack.org, Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , cgroups@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3] vmalloc: Fix accounting with i915 Message-ID: References: <20241211202538.168311-1-willy@infradead.org> Precedence: bulk X-Mailing-List: cgroups@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: <20241211202538.168311-1-willy@infradead.org> On Wed 11-12-24 20:25:37, Matthew Wilcox wrote: > If the caller of vmap() specifies VM_MAP_PUT_PAGES (currently only the > i915 driver), we will decrement nr_vmalloc_pages and MEMCG_VMALLOC in > vfree(). These counters are incremented by vmalloc() but not by vmap() > so this will cause an underflow. Check the VM_MAP_PUT_PAGES flag before > decrementing either counter. > > Fixes: b944afc9d64d (mm: add a VM_MAP_PUT_PAGES flag for vmap) > Cc: stable@vger.kernel.org > Signed-off-by: Matthew Wilcox (Oracle) > Acked-by: Johannes Weiner Acked-by: Michal Hocko Thanks! > --- > mm/vmalloc.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index f009b21705c1..5c88d0e90c20 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3374,7 +3374,8 @@ void vfree(const void *addr) > struct page *page = vm->pages[i]; > > BUG_ON(!page); > - mod_memcg_page_state(page, MEMCG_VMALLOC, -1); > + if (!(vm->flags & VM_MAP_PUT_PAGES)) > + mod_memcg_page_state(page, MEMCG_VMALLOC, -1); > /* > * High-order allocs for huge vmallocs are split, so > * can be freed as an array of order-0 allocations > @@ -3382,7 +3383,8 @@ void vfree(const void *addr) > __free_page(page); > cond_resched(); > } > - atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages); > + if (!(vm->flags & VM_MAP_PUT_PAGES)) > + atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages); > kvfree(vm->pages); > kfree(vm); > } > -- > 2.45.2 -- Michal Hocko SUSE Labs