linux-kernel - Re: [PATCH 1/4] mm/memory: convert do_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZKNY7XOQFYJoHrBS@casper.infradead.org>
Date:   Tue, 4 Jul 2023 00:25:33 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org
Subject: Re: [PATCH 1/4] mm/memory: convert do_page_mkwrite() to use folios

On Sun, Jul 02, 2023 at 10:58:47PM -0700, Sidhartha Kumar wrote:
> @@ -2947,14 +2947,14 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
>  	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
>  		return ret;
>  	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
> -		lock_page(page);
> -		if (!page->mapping) {
> -			unlock_page(page);
> +		folio_lock(folio);
> +		if (!folio_mapping(folio)) {

You don't need to call folio_mapping() here.  folio->mapping works
absolutely fine in this circumstance.  In fact, you may have broken a
driver with this change.  I can elaborate more, but I'm not quite in the
mood to do that right now.