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d=linutronix.de; s=2020e; t=1662099829; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=FNXlO5JIHjp6Q9jkavDrFQejyN8sLjCcSCk1NEtTtuM=; b=HZtJcpa5vxYATLgUzjtVGzhwNVCLOeNDJ+ONSgS5kxaY8UkTVlSUh1wXMjdIyoPHKWkhdp d1pb5xRDehd/PUDg== From: Sebastian Andrzej Siewior To: Kent Overstreet Cc: Suren Baghdasaryan , akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH RESEND 04/28] mm: move mmap_lock assert function definitions Message-ID: References: <20220901173516.702122-1-surenb@google.com> <20220901173516.702122-5-surenb@google.com> <20220901202409.e2fqegqghlijkzey@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220901202409.e2fqegqghlijkzey@moria.home.lan> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662099832; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FNXlO5JIHjp6Q9jkavDrFQejyN8sLjCcSCk1NEtTtuM=; b=oDxF2Q4KEUjWVM8CBIi/JNP/J/0lwgiDdq33JNIUGVMN8DpfNruArb/h8cB8ldUGlopZs8 Dw2ydBX4/hS3eblkMJwel39VHbDwlKlIJG7wu2QXev0wm3HEunltIW1Q5pQu20ciwVXz1d ZSMWgeWvjNIeJWuWRFnI0/BIVTkqQGk= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=OMPrOq4c; dkim=pass header.d=linutronix.de header.s=2020e header.b=HZtJcpa5; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf27.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662099832; a=rsa-sha256; cv=none; b=xJGLFU/14mjpV4tNo7fnFFJVQBdIE84ZHju096phsXkIlkchybTLbsXZ+POCGqexbBhI+1 MdfgoD+IB23wLZcJ85021m0MgJ+7CAtCgZEeh3DPbh/k2vpBNVsA8lEi5V9ErELHy3unNM g05SwkkOR/L5K99/m6mXc6ZVNpUiQKo= Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=OMPrOq4c; dkim=pass header.d=linutronix.de header.s=2020e header.b=HZtJcpa5; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf27.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de X-Rspamd-Queue-Id: E4BE640096 X-Stat-Signature: 3bi8siqxajy1xaocyntkknbgpmpyx64p X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1662099831-93074 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 2022-09-01 16:24:09 [-0400], Kent Overstreet wrote: > > --- a/include/linux/mmap_lock.h > > +++ b/include/linux/mmap_lock.h > > @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write) > > > > #endif /* CONFIG_TRACING */ > > > > +static inline void mmap_assert_locked(struct mm_struct *mm) > > +{ > > + lockdep_assert_held(&mm->mmap_lock); > > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm); > > These look redundant to me - maybe there's a reason the VM developers want both, > but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since > that's the standard way to write that assertion. Exactly. rwsem_is_locked() returns true only if the lock is "locked" not necessary by the caller. lockdep_assert_held() checks that the lock is locked by the caller - this is the important part. Sebastian