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Date: Wed, 24 Apr 2024 18:59:01 -0700
From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
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Subject: Re: [PATCH v6 00/37] Memory allocation profiling
Message-ID: <202404241852.DC4067B7@keescook>
References: <20240321163705.3067592-1-surenb@google.com>
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On Thu, Mar 21, 2024 at 09:36:22AM -0700, Suren Baghdasaryan wrote:
> Low overhead [1] per-callsite memory allocation profiling. Not just for
> debug kernels, overhead low enough to be deployed in production.

Okay, I think I'm holding it wrong. With next-20240424 if I set:

CONFIG_CODE_TAGGING=y
CONFIG_MEM_ALLOC_PROFILING=y
CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y

My test system totally freaks out:

..
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
Oops: general protection fault, probably for non-canonical address 0xc388d881e4808550: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 PID: 0 Comm: swapper Not tainted 6.9.0-rc5-next-20240424 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
RIP: 0010:__kmalloc_node_noprof+0xcd/0x560

Which is:

__kmalloc_node_noprof+0xcd/0x560:
__slab_alloc_node at mm/slub.c:3780 (discriminator 2)
(inlined by) slab_alloc_node at mm/slub.c:3982 (discriminator 2)
(inlined by) __do_kmalloc_node at mm/slub.c:4114 (discriminator 2)
(inlined by) __kmalloc_node_noprof at mm/slub.c:4122 (discriminator 2)

Which is:

        tid = READ_ONCE(c->tid);

I haven't gotten any further than that; I'm EOD. Anyone seen anything
like this with this series?

-Kees

-- 
Kees Cook