From: Guenter Roeck <linux@roeck-us.net>
To: 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: Kernel BUG with loongarch and CONFIG_KFENCE and CONFIG_DEBUG_SG
Date: Wed, 27 Mar 2024 12:11:12 -0700 [thread overview]
Message-ID: <c352829b-ed75-4ffd-af6e-0ea754e1bf3d@roeck-us.net> (raw)
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.
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
next reply other threads:[~2024-03-27 19:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-27 19:11 Guenter Roeck [this message]
2024-03-27 19:33 ` Kernel BUG with loongarch and CONFIG_KFENCE and CONFIG_DEBUG_SG Xi Ruoyao
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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