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

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Message-ID: <Zs3WouJpDk3AWV4D@tiehlicka>
Date: Tue, 27 Aug 2024 15:37:38 +0200
From: Michal Hocko <mhocko@...e.com>
To: Uladzislau Rezki <urezki@...il.com>
Cc: 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 27-08-24 14:47:30, Uladzislau Rezki wrote:
> On Tue, Aug 27, 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.
-- 
Michal Hocko
SUSE Labs