linux-kernel - Re: [PATCH] mm/vmalloc: warn only once when vmalloc detect invalid gfp flags

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Message-ID: <aRvGfsZMRIQuC3TQ@fedora>
Date: Mon, 17 Nov 2025 17:06:06 -0800
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: David Heidelberg <david@...t.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Uladzislau Rezki <urezki@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org
Subject: Re: [PATCH] mm/vmalloc: warn only once when vmalloc detect invalid
 gfp flags

On Tue, Nov 18, 2025 at 01:51:23AM +0100, David Heidelberg wrote:
> On 18/11/2025 01:34, Vishal Moola (Oracle) wrote:
> > On Tue, Nov 18, 2025 at 01:05:57AM +0100, David Heidelberg via B4 Relay wrote:
> > > From: David Heidelberg <david@...t.cz>
> > > 
> > > Without WARN_ONCE, the logs get spammed immediately after the boot,
> > > on devices as OnePlus 6T (Snapdragon 845).
> > 
> > Do you have any snippets of the logs? There'll be a particularly helpful
> > section that says "Unexpected gfp:"...
> 
> I didn't save it, thou I'll run the kernel with all logs again tomorrow,
> what I remember it was "__GFP_ACCOUNT" in unexpected section.

Gotcha. That's particular flag has been added to the whitelist as of
today. Hopefully there are no others.

> > 
> > > Fixes: 7179b2256315 ("mm/vmalloc: warn on invalid vmalloc gfp flags")
> > 
> > For some context, this patch begins enforcing the gfp flags passed into
> > vmalloc(). If the logs are getting spammed, that means the device is
> > calling vmalloc() with some unsupported gfp flag, many many times.
> 
> Yes, it was full dmesg buffer just after the boot and I think ongoing.
>
> > 
> > > Signed-off-by: David Heidelberg <david@...t.cz>
> > > ---
> > > I'm not 100% sure this is the right solution, but having WARN_ONCE or
> > > rate limited warnings here helps a lot on devices as OnePlus 6 (sdm845).
> > 
> > Can you check if it still happens on today's mm-new?
> > I just sent a new version earlier today that also masks off
> > __GFP_ACCOUNT, and had an iteration earlier that added
> > __GFP_HARDWALL.
> 
> I can try tomorrow, any chance it'll bubble into next-20251118?

I'm not sure, Andrew should know?

> Thank you
> David
> 
> -- 
> David Heidelberg
>