linux-kernel - Re: [RESEND PATCH v1] mm/vmalloc: fix page mapping if vm_area_alloc_pages() with high order fallback to order 0

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: <Zs3w3k7-bzCYa3KC@pc636>
Date: Tue, 27 Aug 2024 17:29:34 +0200
From: Uladzislau Rezki <urezki@...il.com>
To: Michal Hocko <mhocko@...e.com>
Cc: Uladzislau Rezki <urezki@...il.com>, Hailong Liu <hailong.liu@...o.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Barry Song <21cnbao@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Tangquan Zheng <zhengtangquan@...o.com>, stable@...r.kernel.org,
	Baoquan He <bhe@...hat.com>, Matthew Wilcox <willy@...radead.org>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v1] mm/vmalloc: fix page mapping if
 vm_area_alloc_pages() with high order fallback to order 0

On Tue, Aug 27, 2024 at 03:37:38PM +0200, Michal Hocko wrote:
> On Tue 27-08-24 14:47:30, Uladzislau Rezki wrote:
> > On Tue, Aug 26, 2024 at 08:49:35AM +0200, Michal Hocko wrote:
> [...]
> > > > 2. High-order allocations. Do you think we should not care much about
> > > > it when __GFP_NOFAIL is set? Same here, there is a fallback for order-0
> > > > if "high" fails, it is more likely NO_FAIL succeed for order-0. Thus
> > > > keeping NOFAIL for high-order sounds like not a good approach to me.
> > > 
> > > We should avoid high order allocations with GFP_NOFAIL at all cost.
> > > 
> > What do you propose here? Fail such request?
> 
> We shouldn't have any hard requirements for higher order allocations in the vmalloc
> right? In other words we can always fallback to base pages.
>
We always drop NOFAIL for high-order, if it fails we fall-back to
order-0. I got the feeling that you wanted just bail-out fully if
high-order and NOFAIL.

--
Uladzislau Rezki