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Subject: Re: [tip:x86/mm] [x86/mm/tlb]  209954cbc7:
 WARNING:at_arch/x86/mm/tlb.c:#flush_tlb_func
From: Rik van Riel <riel@surriel.com>
To: kernel test robot <oliver.sang@intel.com>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, 
	x86@kernel.org, Ingo Molnar <mingo@kernel.org>, Dave Hansen
 <dave.hansen@intel.com>,  Linus Torvalds <torvalds@linux-foundation.org>,
 Peter Zijlstra <peterz@infradead.org>, Mel Gorman	 <mgorman@suse.de>
Date: Thu, 05 Dec 2024 09:21:13 -0500
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On Thu, 2024-12-05 at 16:43 +0800, kernel test robot wrote:
>=20

> [=C2=A0 210.338271][ T4668] ------------[ cut here ]------------
> [ 210.343902][ T4668] WARNING: CPU: 38 PID: 4668 at
> arch/x86/mm/tlb.c:815 flush_tlb_func (arch/x86/mm/tlb.c:815)

Huh, this is the warning below:

       WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen);

This cannot happen on remote CPUs, because they
will check whether f->mm !=3D loaded_mm, but with
my patches it can happen on the _local_ CPU, if:

The current CPU:
- Is in the mm_cpumask for another mm
- Tries to flush the TLB for that other mm
- Calls flush_tlb_func locally with f->mm being
  that other mm.

It should be a fairly easy fix, pulling the
/* Can only happen on remote CPUs */ thing
out from the !local condition, since it can
now happen locally :)

I'll send a fix in a little bit.

--=20
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