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Fri, 02 Oct 2020 10:53:42 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH 2/2] mm/frame-vec: use FOLL_LONGTERM Date: Fri, 2 Oct 2020 19:53:03 +0200 Message-Id: <20201002175303.390363-2-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201002175303.390363-1-daniel.vetter@ffwll.ch> References: <20201002175303.390363-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201002_135344_272229_0FB1666C X-CRM114-Status: GOOD ( 21.64 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:443 listed in] [list.dnswl.org] 0.0 SPF_NONE SPF: sender does not publish an SPF Record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc@vger.kernel.org, Jan Kara , Daniel Vetter , LKML , linux-mm@kvack.org, =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , John Hubbard , Daniel Vetter , Andrew Morton , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org For $reasons I've stumbled over this code and I'm not sure the change to the new gup functions in 55a650c35fea ("mm/gup: frame_vector: convert get_user_pages() --> pin_user_pages()") was entirely correct. This here is used for long term buffers (not just quick I/O) like RDMA, and John notes this in his patch. But I thought the rule for these is that they need to add FOLL_LONGTERM, which John's patch didn't do. There is already a dax specific check (added in b7f0554a56f2 ("mm: fail get_vaddr_frames() for filesystem-dax mappings")), so this seems like the prudent thing to do. Signed-off-by: Daniel Vetter Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org --- Hi all, I stumbled over this and figured typing this patch can't hurt. Really just to maybe learn a few things about how gup/pup is supposed to be used (we have a bit of that in drivers/gpu), this here isn't really ralated to anything I'm doing. I'm also wondering whether the explicit dax check should be removed, since FOLL_LONGTERM should take care of that already. -Daniel --- mm/frame_vector.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 5d34c9047e9c..3507e09cb3ff 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -35,7 +35,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; - unsigned int gup_flags = FOLL_WRITE | FOLL_FORCE; + unsigned int gup_flags = FOLL_WRITE | FOLL_FORCE | FOLL_LONGTERM; int ret = 0; int err; int locked;