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

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Message-ID: <aRw8-7Ox5TPewpw_@milan>
Date: Tue, 18 Nov 2025 10:31:39 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Cc: david@...t.cz, 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 Mon, Nov 17, 2025 at 05:16:45PM -0800, 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).
> > 
> > Fixes: 7179b2256315 ("mm/vmalloc: warn on invalid vmalloc gfp flags")
> > 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).
> > 
> > Please let me know what you think.
> > ---
> >  mm/vmalloc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 49e0b68768d73..2a3ee17093d6e 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -3934,8 +3934,8 @@ static gfp_t vmalloc_fix_flags(gfp_t flags)
> >  	gfp_t invalid_mask = flags & ~GFP_VMALLOC_SUPPORTED;
> >  
> >  	flags &= GFP_VMALLOC_SUPPORTED;
> > -	WARN(1, "Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
> > -			invalid_mask, &invalid_mask, flags, &flags);
> > +	WARN_ONCE(1, "Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n"
> 
> You accidentally deleted the comma here. 
> 
> Once we've found all gfp the callers currently use, we should never be
> hitting this warning, so ratelimiting won't matter. Either way is fine
> by me though if you still want to fix and resend this.
> 
IMO, it is worth to use ONCE variant to suppress spamming.

--
Uladzislau Rezki