From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 52C8236E47E; Tue, 10 Mar 2026 10:50:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773139816; cv=none; b=tWt8PydVmdQPvu7L8K7lTumPQnEVdOt/auczWjSba+yT0idDFaeiOrZmnN8xfmovGTSyqRa3ilm53DyzVu6dWkbum59bJq5lDGXDMVTbNBjXL2AjtyHYEJMpfpXpUN+fnjkmamcZBOQkZ7X2zakH/zWSKyxcWJHqdqJB9i+DwMg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773139816; c=relaxed/simple; bh=lv/Ndv2cGNSU8aZpViy8aWp8+gArFm7Nl+ywKCt1J2w=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:References: In-Reply-To:Content-Type; b=iNJg3yWWB0dOa1JrPYpaY+iQtWPC+c2UdoZfPEN/JaYfaymCBq9aVT8WTd+nhYeVxMSn78wiMNfSgZGY0QjjcF2/TxLTkBparlq12bXjKeJ1wsSC+LLjne/kq5vNacsAesU3QHMsHCHS2kI6/WoR6AnPBrCmEsMrz+bJ8O1Jank= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mz8OWw/n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mz8OWw/n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDB5AC19423; Tue, 10 Mar 2026 10:50:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773139816; bh=lv/Ndv2cGNSU8aZpViy8aWp8+gArFm7Nl+ywKCt1J2w=; h=Date:From:Subject:To:Cc:References:In-Reply-To:From; b=Mz8OWw/nAP45YmbN1qfVWB3MpD98Hq/VK4sTreUz7bDKtUvA6dRpWW/XE73U4ugEG HhK4RLYI4/BTv0PJfPT90p+fYzsFN01N89hUx7C94T9HjSoaosuONwyCThwlQtoYJQ Wrg01OKBiiEMs3wpPqXT2AaQBxJNENgHYrypN/aMO+uyGPgOXNmnaUF3ijVO5wqqVb 89W5niv3FFHxKAfnIe8mubdmZSPDym/rdkgsKua1F4DFVyv9hwxIvfeeLSuPKZRS/8 9O8mqN/poUxM/G3DmidqbMQj8phGfEZ50QXVjxgHCRGO3PYM5dnyFadj/po+kEVEZs I+EFrtjnwVVJg== Message-ID: Date: Tue, 10 Mar 2026 11:50:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: vbabka@kernel.org Subject: Re: [PATCH] mm/debug: optimize once judgment with clang Content-Language: en-US To: Xie Yuanbin , rppt@kernel.org, david.laight.linux@gmail.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, surenb@google.com, mhocko@suse.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20260309153405.20130-1-qq570070308@gmail.com> In-Reply-To: <20260309153405.20130-1-qq570070308@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/9/26 16:34, Xie Yuanbin wrote: > commit 242b872239f6a7deacbc ("include/linux/once_lite.h: fix judgment in > WARN_ONCE with clang") helps optimize performance and size under the > clang compiler, but the modification is not complete. > > Port the modification to VM_WARN_ON_ONCE_PAGE(), VM_WARN_ON_ONCE_FOLIO(), > VM_WARN_ON_ONCE_MM() and VM_WARN_ON_ONCE_VMA(). > > Cc: Mike Rapoport > Cc: David Laight > Cc: Andrew Morton > Signed-off-by: Xie Yuanbin We don't need to make debug code (hence perf doesn't matter there) more ugly just for clang's sake, I think. > --- > include/linux/mmdebug.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h > index ab60ffba08f5..a167c5aa525e 100644 > --- a/include/linux/mmdebug.h > +++ b/include/linux/mmdebug.h > @@ -60,7 +60,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); > static bool __section(".data..once") __warned; \ > int __ret_warn_once = !!(cond); \ > \ > - if (unlikely(__ret_warn_once && !__warned)) { \ > + if (unlikely(__ret_warn_once) && unlikely(!__warned)) { \ > dump_page(page, "VM_WARN_ON_ONCE_PAGE(" __stringify(cond)")");\ > __warned = true; \ > WARN_ON(1); \ > @@ -80,7 +80,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); > static bool __section(".data..once") __warned; \ > int __ret_warn_once = !!(cond); \ > \ > - if (unlikely(__ret_warn_once && !__warned)) { \ > + if (unlikely(__ret_warn_once) && unlikely(!__warned)) { \ > dump_page(&folio->page, "VM_WARN_ON_ONCE_FOLIO(" __stringify(cond)")");\ > __warned = true; \ > WARN_ON(1); \ > @@ -91,7 +91,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); > static bool __section(".data..once") __warned; \ > int __ret_warn_once = !!(cond); \ > \ > - if (unlikely(__ret_warn_once && !__warned)) { \ > + if (unlikely(__ret_warn_once) && unlikely(!__warned)) { \ > dump_mm(mm); \ > __warned = true; \ > WARN_ON(1); \ > @@ -102,7 +102,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi); > static bool __section(".data..once") __warned; \ > int __ret_warn_once = !!(cond); \ > \ > - if (unlikely(__ret_warn_once && !__warned)) { \ > + if (unlikely(__ret_warn_once) && unlikely(!__warned)) { \ > dump_vma(vma); \ > __warned = true; \ > WARN_ON(1); \