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Sat, 27 Aug 2022 15:37:05 -0700 (PDT) X-Google-Smtp-Source: AA6agR7expqAq6mEeXBKWE4Mh5iw9mIyo52it8G+eTvLFWP1HFVV7eclzHI2juSool4JCGk9Ee0GwA== X-Received: by 2002:a17:902:a98a:b0:173:2b4d:e7df with SMTP id bh10-20020a170902a98a00b001732b4de7dfmr9842739plb.36.1661639824941; Sat, 27 Aug 2022 15:37:04 -0700 (PDT) Received: from localhost ([240d:1a:c0d:9f00:4f2f:926a:23dd:8588]) by smtp.gmail.com with ESMTPSA id z16-20020aa79490000000b00538147b1a38sm426752pfk.160.2022.08.27.15.37.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Aug 2022 15:37:04 -0700 (PDT) Date: Sun, 28 Aug 2022 07:36:57 +0900 (JST) Message-Id: <20220828.073657.766389803686589716.syoshida@redhat.com> To: dan.carpenter@oracle.com Cc: linux-mm@kvack.org Subject: Re: [bug report] mm/gup.c: Fix return value for __gup_longterm_locked() From: Shigeru Yoshida In-Reply-To: References: X-Mailer: Mew version 6.8 on Emacs 28.1 Mime-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: Text/Plain; 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t=1661639829; a=rsa-sha256; cv=none; b=Fn/rVQ367cHtYQ4DJz+DSqcEizIq6kv6ct6iDS0cCog9gGjWgBGVpF8e59N1CmBQn8QY2v Y5GbbGixVb8jnjuRvTFsaUJr+cQKDZ0iKjFMmGjO8vDwBE8K09TJijnBUHwQtt3w3sDO8t jX72GRCbTM1Ii6XfGZ8F0XUzN64gh+g= X-Stat-Signature: csas1hihtn4d7bhdxo4bhw77fbpradhz X-Rspamd-Queue-Id: 373FEC0025 Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=cCs4lmOk; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf10.hostedemail.com: domain of syoshida@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=syoshida@redhat.com X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1661639828-995212 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: Hi Dan, On Thu, 25 Aug 2022 10:49:27 +0300, Dan Carpenter wrote: > Hello Shigeru Yoshida, > > The patch 35f9c4607f9e: "mm/gup.c: Fix return value for > __gup_longterm_locked()" from Aug 22, 2022, leads to the following > Smatch static checker warning: > > mm/gup.c:2089 __gup_longterm_locked() > error: uninitialized symbol 'rc'. > > mm/gup.c > 2064 static long __gup_longterm_locked(struct mm_struct *mm, > 2065 unsigned long start, > 2066 unsigned long nr_pages, > 2067 struct page **pages, > 2068 struct vm_area_struct **vmas, > 2069 unsigned int gup_flags) > 2070 { > 2071 unsigned int flags; > 2072 long rc, nr_pinned_pages; > 2073 > 2074 if (!(gup_flags & FOLL_LONGTERM)) > 2075 return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, > 2076 NULL, gup_flags); > 2077 flags = memalloc_pin_save(); > 2078 do { > 2079 nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages, > 2080 pages, vmas, NULL, > 2081 gup_flags); > 2082 if (nr_pinned_pages <= 0) > > > This doesn't work if if fails on the first iteration. But also I'm > surprised that we are return -EAGAIN on subsequent iterations... Sorry for late response and thanks for your bug report. Yes, that's my fault. I'll prepare the patch. Thanks, Shigeru > > 2083 break; > 2084 rc = check_and_migrate_movable_pages(nr_pinned_pages, pages, > 2085 gup_flags); > 2086 } while (rc == -EAGAIN); > 2087 memalloc_pin_restore(flags); > 2088 > --> 2089 return rc ? rc : nr_pinned_pages; > 2090 } > > regards, > dan carpenter >