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 30B3D14A611 for ; Thu, 15 Aug 2024 22:35:25 +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=1723761326; cv=none; b=s+v+X7JdIm8hTDcIWygdwCWJksVEw1qphXL9uL+6T61UP2R3Ja1ZvC6ablXPy8OHkBI/jDWRwJ7k+qPVmTVwfIh8OZ3tUg7+ReaCnRycozLTw1+LS2oeL0cb2s9TNvP2NY6fFhdAP8tVZHr0OgeGPGd2/g8jEmtpEJQs6b4xn68= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723761326; c=relaxed/simple; bh=nz2vpWF0gWpmU5TwnjJ4/svSq1c7N9z+UbUg0aGlJMA=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=eDGRQwpdSOm4T9t2l4mwVI0FRZe7d6Bb/4/aQZz8CnJ/1sWSNAIFF0C3pzEV4EPe1GMOGayDTMFNG+7CQrE+xpLlHkNUPna0oviZLr1HWg4hv+zZQZPv4/jZwKEcX8gCPss8bukOb9+BTRsutrmbiwVgfPsCqskoI0xe8RMJz5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=r48m1Ifz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="r48m1Ifz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71F9BC32786; Thu, 15 Aug 2024 22:35:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1723761325; bh=nz2vpWF0gWpmU5TwnjJ4/svSq1c7N9z+UbUg0aGlJMA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=r48m1IfzWwY8XNCkaYv/YCKAzJM+/FW/Rc30nfLBjG41id+q0Ji5+B+7rPEuNny/L Af+ISgcAfGDTY7Ot41P/wWo68nqBI+OoI8wk0qDZpI3+9XT2pQzxS3XwAMAb+KK9r8 xOBIi1xHAo+NFXQ98VYnjZMD7wbeMNy9kDEDzz3o= Date: Thu, 15 Aug 2024 15:35:24 -0700 From: Andrew Morton To: Huan Yang Cc: usamaarif642@gmail.com, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, opensource.kernel@vivo.com Subject: Re: [PATCH] mm: move the easily assessable conditions forward Message-Id: <20240815153524.6bb7c26dc32feb93dd1ba513@linux-foundation.org> In-Reply-To: <20240815083102.653820-1-link@vivo.com> References: <20240815083102.653820-1-link@vivo.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Thu, 15 Aug 2024 16:31:01 +0800 Huan Yang wrote: > Current try_to_map_unused_to_zeropage try to use shared zero page to > save some memory of sub page. > > If forbids zeropage, no need to do anything rather than attempting to > assess wthether to use it afterwards. > > ... > > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -192,6 +192,9 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); > > + if (mm_forbids_zeropage(pvmw->vma->vm_mm)) > + return false; > + > if (PageMlocked(page) || (pvmw->vma->vm_flags & VM_LOCKED)) > return false; > > @@ -204,7 +207,7 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, > contains_data = memchr_inv(addr, 0, PAGE_SIZE); > kunmap_local(addr); > > - if (contains_data || mm_forbids_zeropage(pvmw->vma->vm_mm)) > + if (contains_data) > return false; > Looks sensible. I'll add it as a fixup to "mm: remap unused subpages to shared zeropage when splitting isolated thp".