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Date: Fri, 21 Nov 2025 08:29:45 +0100
From: Christoph Hellwig <hch@lst.de>
To: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>, Christoph Hellwig <hch@lst.de>,
	linux-xfs@vger.kernel.org, Biju Das <biju.das.jz@bp.renesas.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"hch@infradead.org" <hch@infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"urezki@gmail.com" <urezki@gmail.com>
Subject: Re: [PATCH v3 0/4] make vmalloc gfp flags usage more apparent
Message-ID: <20251121072945.GA30438@lst.de>
References: <TY3PR01MB11346E8536B69E11A9A9DAB0886D6A@TY3PR01MB11346.jpnprd01.prod.outlook.com> <aRyn7Ibaqa5rlHHx@fedora> <aRzPqYfXc6mtR1U9@casper.infradead.org> <aR4SmclGax8584IJ@fedora>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Nov 19, 2025 at 10:55:21AM -0800, Vishal Moola (Oracle) wrote:
> > 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.

I'm not a fan of __GFP_NOLOCKDEP, but it is a valid hint for the
allocator, so it should be supported.