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Mon, 31 Mar 2025 13:58:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id MmhmLn+f6meqLAAAD6G6ig (envelope-from ); Mon, 31 Mar 2025 13:58:23 +0000 Date: Mon, 31 Mar 2025 15:58:22 +0200 From: Oscar Salvador To: Baoquan He Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/7] mm/gup: Fix the outdated code comments above get_user_pages_unlocked() Message-ID: References: <20250330121718.175815-1-bhe@redhat.com> <20250330121718.175815-4-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250330121718.175815-4-bhe@redhat.com> X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B363740017 X-Stat-Signature: q3atxsy7pqokpwzqy5s9ubobbhn7cfch X-HE-Tag: 1743429505-788573 X-HE-Meta: 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 x8A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000014, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Mar 30, 2025 at 08:17:13PM +0800, Baoquan He wrote: > Since commit f0818f472d8d ("mm: gup: add get_user_pages_locked > and get_user_pages_unlocked"), get_user_pages() doesn't need to have > mmap_lock held anymore. It calls __get_user_pages_locked() which > can acquire and drop the mmap_lock internaly. Yes, __get_user_pages_locked() can aquire and drop the lock, but AFAICS get_user_pages() always calls __get_user_pages_locked() with locked=1, which means that is holding the lock, right? > Hence remove the incorrect code comments now. > > Signed-off-by: Baoquan He > --- > mm/gup.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 8788105daee8..3345a065c2cb 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2702,19 +2702,9 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, > EXPORT_SYMBOL(get_user_pages); > > /* > - * get_user_pages_unlocked() is suitable to replace the form: > - * > - * mmap_read_lock(mm); > - * get_user_pages(mm, ..., pages, NULL); > - * mmap_read_unlock(mm); > - * > - * with: > - * > - * get_user_pages_unlocked(mm, ..., pages); > - * > - * It is functionally equivalent to get_user_pages_fast so > - * get_user_pages_fast should be used instead if specific gup_flags > - * (e.g. FOLL_FORCE) are not required. > + * get_user_pages_unlocked() is functionally equivalent to > + * get_user_pages_fast so get_user_pages_fast should be used instead > + * if specific gup_flags (e.g. FOLL_FORCE) are not required. > */ > long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, > struct page **pages, unsigned int gup_flags) > -- > 2.41.0 > > -- Oscar Salvador SUSE Labs