From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A280C1D12E0; Thu, 21 Nov 2024 12:40:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732192838; cv=none; b=eDIUH5bHda6QTj4/d7zLsl+5lckYh1F/Et+s4uQqgWAJwb7nJJPDHKzANj9vawzDHvbdA0AAxIVcHm5Q6ac1oka+f0om9XoPQLgZJqxgtTaiWdB3kbhuWOEmmARpsBKpG2RWl5hf0/akhqaj3iXOU1VS6PCbWky3ZpC17/ENY84= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732192838; c=relaxed/simple; bh=yIq/EMeFPW5kEsCkl9Aphuk7NiHKWxE+K7aOyaxDZzk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SfMPrFY8fE9Y2HHUu3xyYA8D9q85E3vbZtuX0zyxKAdnTkptC/0XDUBsoKtDmkVdKXCteAdo7d26VA8hoL3IR35oTGsmeTtlSQ/Hg2XleKxWKSX3gCDUjp5d8PBnrL6vTQczwyjf6uXQZYZ7XLX4Kjge3MWgsPB6j340JIASUJg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=AQZ2dw3G; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="AQZ2dw3G" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ikpAnH13gbp0BHe1sYaGxmFI2nIUUInCIR7xIHSqhjw=; b=AQZ2dw3G7cIbip5y5YOVoD0RtD 927AGxDlm/cKkwl8CrIw8V7+iEJgbmopNa0dPo0Zsp4AdtEUj7FQ508lfvuTUhEWDud29AnRJB5vn iar09XeXACJREwkkIsnq9KmIXBafd4P1n0hlrwfjuHR4+akH2DOXJ++kkHlk16vSgjLp49hS5LXqD KMwdWMXDVPDFpTZj0kT1gOlOtYuEkZVfqf/S85vBqsjk2coQuXtvV7aoM+DsXkzB24IcAy0qq6qnT D++kovSxCKKB1EY2C2p9m2vSTrshUuugrr4x7V0UbTyYu9VslMnyzX3OTCjww98AVVQHX2ScvJiyD Yp9aWmuw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tE6Tk-00000000a0U-1YEf; Thu, 21 Nov 2024 12:40:12 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 8FDC730068B; Thu, 21 Nov 2024 13:40:11 +0100 (CET) Date: Thu, 21 Nov 2024 13:40:11 +0100 From: Peter Zijlstra To: Andrii Nakryiko Cc: linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, surenb@google.com, mjguzik@gmail.com, brauner@kernel.org, jannh@google.com, mhocko@kernel.org, vbabka@suse.cz, shakeel.butt@linux.dev, hannes@cmpxchg.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, david@redhat.com, arnd@arndb.de, richard.weiyang@gmail.com, zhangpeng.00@bytedance.com, linmiaohe@huawei.com, viro@zeniv.linux.org.uk, hca@linux.ibm.com Subject: Re: [PATCH v4 tip/perf/core 1/4] mm: Convert mm_lock_seq to a proper seqcount Message-ID: <20241121124011.GK24774@noisy.programming.kicks-ass.net> References: <20241028010818.2487581-1-andrii@kernel.org> <20241028010818.2487581-2-andrii@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241028010818.2487581-2-andrii@kernel.org> On Sun, Oct 27, 2024 at 06:08:15PM -0700, Andrii Nakryiko wrote: > +/* > + * Drop all currently-held per-VMA locks. > + * This is called from the mmap_lock implementation directly before releasing > + * a write-locked mmap_lock (or downgrading it to read-locked). > + * This should normally NOT be called manually from other places. > + * If you want to call this manually anyway, keep in mind that this will release > + * *all* VMA write locks, including ones from further up the stack. > + */ > +static inline void vma_end_write_all(struct mm_struct *mm) > +{ > + mmap_assert_write_locked(mm); > + /* > + * Nobody can concurrently modify mm->mm_lock_seq due to exclusive > + * mmap_lock being held. > + */ You can write: ASSERT_EXCLUSIVE_WRITER(mm->mm_lock_seq); instead of that comment. Then KCSAN will validate the claim. > + mm_lock_seqcount_end(mm); > +}