linux-hardening - Re: [REGRESSION] bpf verifier slowdown due to vrealloc() change since 6.15-rc6

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Message-ID: <c36245a48149a12180ec710c65d317a12cdfa020.camel@gmail.com>
Date: Thu, 15 May 2025 11:31:09 -0700
From: Eduard Zingerman <eddyz87@...il.com>
To: Kees Cook <kees@...nel.org>, Shung-Hsi Yu <shung-hsi.yu@...e.com>
Cc: bpf@...r.kernel.org, linux-mm@...ck.org, Andrii Nakryiko
 <andrii@...nel.org>,  Ihor Solodrai <ihor.solodrai@...ux.dev>, Andrew
 Morton <akpm@...ux-foundation.org>, Michal Hocko	 <mhocko@...e.com>,
 Vlastimil Babka <vbabka@...e.cz>, Uladzislau Rezki	 <urezki@...il.com>,
 linux-kernel@...r.kernel.org, 	linux-hardening@...r.kernel.org,
 regressions@...ts.linux.dev, Greg Kroah-Hartman	
 <gregkh@...uxfoundation.org>, Alexei Starovoitov <ast@...nel.org>, Daniel
 Borkmann <daniel@...earbox.net>, Pawan Gupta
 <pawan.kumar.gupta@...ux.intel.com>
Subject: Re: [REGRESSION] bpf verifier slowdown due to vrealloc() change
 since 6.15-rc6

On Thu, 2025-05-15 at 08:47 -0700, Kees Cook wrote:
> On Thu, May 15, 2025 at 09:12:25PM +0800, Shung-Hsi Yu wrote:
> > Bisect was done by Pawan and got to commit a0309faf1cb0 "mm: vmalloc:
> > support more granular vrealloc() sizing"[2]. To further zoom in the
> 
> Can you try this patch? It's a clear bug fix, but if it doesn't improve
> things, I have another idea to rearrange the memset.

I tried this patch on top of the commit 82f2b0b97b36 ("Linux 6.15-rc6").
W/o the patch I observe the slowdown, test times out after 120 seconds,
with the patch test finishes in 3 seconds.

[...]