From: Xi Ruoyao <xry111@xry111.site>
To: Guenter Roeck <linux@roeck-us.net>, loongarch@lists.linux.dev
Cc: Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com
Subject: Re: Kernel BUG with loongarch and CONFIG_KFENCE and CONFIG_DEBUG_SG
Date: Thu, 28 Mar 2024 03:33:03 +0800 [thread overview]
Message-ID: <4d2373e3f0694fd02137a72181d054ee2ebcca45.camel@xry111.site> (raw)
In-Reply-To: <c352829b-ed75-4ffd-af6e-0ea754e1bf3d@roeck-us.net>
On Wed, 2024-03-27 at 12:11 -0700, Guenter Roeck wrote:
> Hi,
>
> when enabling both CONFIG_KFENCE and CONFIG_DEBUG_SG, I get the following
> backtraces when running loongarch images in qemu.
>
> [ 2.496257] kernel BUG at include/linux/scatterlist.h:187!
> ...
> [ 2.501925] Call Trace:
> [ 2.501950] [<9000000004ad59c4>] sg_init_one+0xac/0xc0
> [ 2.502204] [<9000000004a438f8>] do_test_kpp+0x278/0x6e4
> [ 2.502353] [<9000000004a43dd4>] alg_test_kpp+0x70/0xf4
> [ 2.502494] [<9000000004a41b48>] alg_test+0x128/0x690
> [ 2.502631] [<9000000004a3d898>] cryptomgr_test+0x20/0x40
> [ 2.502775] [<90000000041b4508>] kthread+0x138/0x158
> [ 2.502912] [<9000000004161c48>] ret_from_kernel_thread+0xc/0xa4
>
> The backtrace is always similar but not exactly the same. It is always
> triggered from cryptomgr_test, but not always from the same test.
>
> Analysis shows that with CONFIG_KFENCE active, the address returned from
> kmalloc() and friends is not always below vm_map_base. It is allocated by
> kfence_alloc() which at least sometimes seems to get its memory from an
> address space above vm_map_base. This causes virt_addr_valid() to return
> false for the affected objects.
Oops, Xuerui has been haunted by some "random" kernel crashes only
occurring with CONFIG_KFENCE=y for months but we weren't able to triage
the issue:
https://github.com/loongson-community/discussions/issues/34
Maybe the same issue or not.
> I have only seen this if CONFIG_DEBUG_SG is enabled because sg_set_buf()
> otherwise does not call virt_addr_valid(), but I found that many memory
> allocation calls return addresses above vm_map_base, making this a
> potential problem when running loongarch images with CONFIG_KFENCE enabled
> whenever some code calls virt_addr_valid().
>
> I don't know how to solve the problem, but I did notice that virt_to_page()
> does handle situations with addr >= vm_map_base. Maybe a similar solution
> would be possible for virt_addr_valid().
>
> Thanks,
> Guenter
>
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2024-03-27 19:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-27 19:11 Kernel BUG with loongarch and CONFIG_KFENCE and CONFIG_DEBUG_SG Guenter Roeck
2024-03-27 19:33 ` Xi Ruoyao [this message]
2024-03-27 23:38 ` Guenter Roeck
2024-03-29 2:17 ` Huacai Chen
2024-03-29 16:32 ` Guenter Roeck
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