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From: Matthew Wilcox <>
To: Yu Zhao <>
Cc: Andrew Morton <>,, Linux-MM <>,
	Uladzislau Rezki <>,, Kees Cook <>
Subject: Re: [Bug 216489] New: Machine freezes due to memory lock
Date: Fri, 16 Sep 2022 09:38:33 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Sep 15, 2022 at 05:59:56PM -0600, Yu Zhao wrote:
> I think this is a manifest of the lockdep warning I reported a couple
> of weeks ago:

That would certainly match the symptoms.

Turning vmap_lock into an NMI-safe lock would be bad.  I don't even know
if we have primitives for that (it's not like you can disable an NMI

I don't quite have time to write a patch right now.  Perhaps something

struct vmap_area *find_vmap_area_nmi(unsigned long addr)
        struct vmap_area *va;

        if (spin_trylock(&vmap_area_lock))
		return NULL;
        va = __find_vmap_area(addr, &vmap_area_root);

        return va;

and then call find_vmap_area_nmi() in check_heap_object().  I may have
the polarity of the return value of spin_trylock() incorrect.

  reply	other threads:[~2022-09-16  8:38 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2022-09-15 20:39 ` [Bug 216489] New: Machine freezes due to memory lock Andrew Morton
2022-09-15 22:42   ` Matthew Wilcox
2022-09-15 23:59     ` Yu Zhao
2022-09-16  8:38       ` Matthew Wilcox [this message]
2022-09-16  9:46         ` Kees Cook
2022-09-16 12:28           ` Uladzislau Rezki
2022-09-16 12:32             ` Uladzislau Rezki
2022-09-16 14:15           ` Matthew Wilcox
2022-09-16 14:42             ` Kees Cook
2022-09-16 18:47             ` Uladzislau Rezki

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