linux-kernel - Re: [PATCH 4/9] mm/page_alloc: optimize code layout for __alloc_pages

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: <20210325121217.GV1719932@casper.infradead.org>
Date:   Thu, 25 Mar 2021 12:12:17 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Net <netdev@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Linux-NFS <linux-nfs@...r.kernel.org>
Subject: Re: [PATCH 4/9] mm/page_alloc: optimize code layout for
 __alloc_pages_bulk

On Thu, Mar 25, 2021 at 11:42:23AM +0000, Mel Gorman wrote:
>  
> -	if (WARN_ON_ONCE(nr_pages <= 0))
> +	if (unlikely(nr_pages <= 0))
>  		return 0;

If we made nr_pages unsigned, we wouldn't need this check at all (ok,
we'd still need to figure out what to do with 0).  But then, if a user
inadvertently passes in -ENOMEM, we'll try to allocate 4 billion pages.
So maybe we should check it.  Gah, API design is hard.