linux-kernel - Re: [PATCH v3 0/4] make vmalloc gfp flags usage more apparent

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Message-ID: <aR4SmclGax8584IJ@fedora>
Date: Wed, 19 Nov 2025 10:55:21 -0800
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: Matthew Wilcox <willy@...radead.org>, Christoph Hellwig <hch@....de>,
	linux-xfs@...r.kernel.org
Cc: Biju Das <biju.das.jz@...renesas.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
	"hch@...radead.org" <hch@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"urezki@...il.com" <urezki@...il.com>
Subject: Re: [PATCH v3 0/4] make vmalloc gfp flags usage more apparent

On Tue, Nov 18, 2025 at 07:57:29PM +0000, Matthew Wilcox wrote:
> On Tue, Nov 18, 2025 at 09:07:56AM -0800, Vishal Moola (Oracle) wrote:
> > On Tue, Nov 18, 2025 at 04:14:01PM +0000, Biju Das wrote:
> > > Hi All,
> > > 
> > > I get below warning with today's next. Can you please suggest how to fix this warning?
> > 
> > Thanks Biju. This has been fixed and will be in whenever Andrews tree
> > gets merged again.
> 
> I see:
> 
> Unexpected gfp: 0x1000000 (__GFP_NOLOCKDEP). Fixing up to gfp: 0x2dc0 (GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN). Fix your code!
> 
> I suspect __GFP_NOLOCKDEP should also be permitted by vmalloc.

As far as I can tell, theres only 1 caller of this.
Christoph started using vmalloc for this xfs call in commit
e2874632a621 ("xfs: use vmalloc instead of vm_map_area for buffer backing memory").

Looks like xfs uses the flag to prevent false positives. Do
we want to continue this? If so, I'll send a patch adding the flag to
the whitelist.