[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] xen/arm: alternative: Don't call vmap() within stop_machine_run()
Hi Jan, On 27/04/2022 07:42, Jan Beulich wrote: On 26.04.2022 22:06, Julien Grall wrote:From: Julien Grall <jgrall@xxxxxxxxxx> Commit 88a037e2cfe1 "page_alloc: assert IRQs are enabled in heap alloc/free" extended the checks in the buddy allocator to catch any use of the helpers from context with interrupts disabled. Unfortunately, the rule is not followed in the alternative code and this will result to crash at boot with debug enabled: (XEN) Xen call trace: (XEN) [<0022a510>] alloc_xenheap_pages+0x120/0x150 (PC) (XEN) [<00000000>] 00000000 (LR) (XEN) [<002736ac>] arch/arm/mm.c#xen_pt_update+0x144/0x6e4 (XEN) [<002740d4>] map_pages_to_xen+0x10/0x20 (XEN) [<00236864>] __vmap+0x400/0x4a4 (XEN) [<0026aee8>] arch/arm/alternative.c#__apply_alternatives_multi_stop+0x144/0x1ec (XEN) [<0022fe40>] stop_machine_run+0x23c/0x300 (XEN) [<002c40c4>] apply_alternatives_all+0x34/0x5c (XEN) [<002ce3e8>] start_xen+0xcb8/0x1024 (XEN) [<00200068>] arch/arm/arm32/head.o#primary_switched+0xc/0x1c The interrupts will be disabled by the state machine in stop_machine_run(), hence why the ASSERT is hit. For now the patch extending the checks has been reverted, but it would be good to re-introduce it (allocation with interrupts disabled is not desirable).We definitely should re-apply that patch once the one here went in. I have commit this patch and also re-apply David's patch. Cheers, -- Julien Grall
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