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Mon, 2 Oct 2023 07:09:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xE9RI6JsGmWqeAAAMHmgww (envelope-from ); Mon, 02 Oct 2023 07:09:22 +0000 Message-ID: <8055dadf-a8ee-6706-79b3-6fc61d77c71e@suse.cz> Date: Mon, 2 Oct 2023 09:09:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v3 1/3] mmap: Fix vma_iterator in error path of vma_merge() Content-Language: en-US To: "Liam R. Howlett" , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jann Horn , Lorenzo Stoakes , Suren Baghdasaryan , Matthew Wilcox , stable@vger.kernel.org References: <20230929183041.2835469-1-Liam.Howlett@oracle.com> <20230929183041.2835469-2-Liam.Howlett@oracle.com> From: Vlastimil Babka In-Reply-To: <20230929183041.2835469-2-Liam.Howlett@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 661FC100005 X-Stat-Signature: pyerdrsr4cz5tw5q6d7agm67i491mfbz X-Rspam-User: X-HE-Tag: 1696230564-365790 X-HE-Meta: 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 UF7Hg+3o Zdl61chTjRvRZm3MBUDe139C2LehbNqrEjluW32/q905ZV9UxIJOphtBNLHcIsAZThywwPAZKQmpIf3xsKmp3z84AOjWT5kP3jMuF3Neyf5bvmQs+CEKEEVrJQHppje9jFYRz0qg3OieXijnNohpzSI1+9Th+BGGosFUf1tW8h3HRIkpGq3Xt74p7rMb908hAaJqnf3vPhbjUU3RNu5NFGzZiLlhOl/nVJmaZXw7ESXww8GD1IU8L584PiCullkFsVlddim2ZtZa0LWqQ84NDNBRk12StfEgOiGiQvKiaxv7/JnScYSOKwrdN8IT+pG2x2ihpUut9j+6y6SXh/e0TfW1hSbUYbwJrXlOUrKTKi0OkI5eQVxxu7NY51Q== 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: On 9/29/23 20:30, Liam R. Howlett wrote: > During the error path, the vma iterator may not be correctly positioned > or set to the correct range. Undo the vma_prev() call by resetting to > the passed in address. Re-walking to the same range will fix the range > to the area previously passed in. > > Users would notice increased cycles as vma_merge() would be called an > extra time with vma == prev, and thus would fail to merge and return. > > Link: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ > Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ > Fixes: 18b098af2890 ("vma_merge: set vma iterator to correct position.") > Cc: stable@vger.kernel.org > Cc: Jann Horn > Signed-off-by: Liam R. Howlett Acked-by: Vlastimil Babka > --- > mm/mmap.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index b56a7f0c9f85..acb7dea49e23 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -975,7 +975,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > > /* Error in anon_vma clone. */ > if (err) > - return NULL; > + goto anon_vma_fail; > > if (vma_start < vma->vm_start || vma_end > vma->vm_end) > vma_expanded = true; > @@ -988,7 +988,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > } > > if (vma_iter_prealloc(vmi, vma)) > - return NULL; > + goto prealloc_fail; > > init_multi_vma_prep(&vp, vma, adjust, remove, remove2); > VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && > @@ -1016,6 +1016,12 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > vma_complete(&vp, vmi, mm); > khugepaged_enter_vma(res, vm_flags); > return res; > + > +prealloc_fail: > +anon_vma_fail: > + vma_iter_set(vmi, addr); > + vma_iter_load(vmi); > + return NULL; > } > > /*