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([240d:1a:c0d:9f00:4f2f:926a:23dd:8588]) by smtp.gmail.com with ESMTPSA id d9-20020a17090a2a4900b001f326ead012sm8584240pjg.37.2022.08.21.11.35.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Aug 2022 11:35:56 -0700 (PDT) From: Shigeru Yoshida To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Shigeru Yoshida , Alistair Popple , syzbot+616ff0452fec30f4dcfd@syzkaller.appspotmail.com Subject: [PATCH] mm/gup.c: Fix return value for __gup_longterm_locked() Date: Mon, 22 Aug 2022 03:35:47 +0900 Message-Id: <20220821183547.950370-1-syoshida@redhat.com> X-Mailer: git-send-email 2.37.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org __get_user_pages_locked() may return the number of pages less than nr_pages. So __gup_longterm_locked() have to return the number of pages __get_user_pages_locked() returns if it succeeded, not nr_pages passed. Fixes: 61c63c2076d9 (mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes) CC: Alistair Popple Reported-by: syzbot+616ff0452fec30f4dcfd@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida --- mm/gup.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 5aa7531a703b..542cf74c59b0 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2068,22 +2068,22 @@ static long __gup_longterm_locked(struct mm_struct *mm, unsigned int gup_flags) { unsigned int flags; - long rc; + long rc, nr_pinned_pages; if (!(gup_flags & FOLL_LONGTERM)) return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, NULL, gup_flags); flags = memalloc_pin_save(); do { - rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, - NULL, gup_flags); - if (rc <= 0) + nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, + NULL, gup_flags); + if (nr_pinned_pages <= 0) break; - rc = check_and_migrate_movable_pages(rc, pages, gup_flags); + rc = check_and_migrate_movable_pages(nr_pinned_pages, pages, gup_flags); } while (rc == -EAGAIN); memalloc_pin_restore(flags); - return rc ? rc : nr_pages; + return rc ? rc : nr_pinned_pages; } static bool is_valid_gup_flags(unsigned int gup_flags) -- 2.37.2