Date: Fri, 22 Jul 2016 14:42:51 -0700 From: John Baldwin <jhb@freebsd.org> To: Roger Pau =?ISO-8859-1?Q?Monn=E9?= <royger@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r303076 - head/sys/dev/fb Message-ID: <3203650.y8tuqEfyUM@ralph.baldwin.cx> In-Reply-To: <201607200929.u6K9Td8S040645@repo.freebsd.org> References: <201607200929.u6K9Td8S040645@repo.freebsd.org>
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On Wednesday, July 20, 2016 09:29:39 AM Roger Pau Monné wrote: > Author: royger > Date: Wed Jul 20 09:29:39 2016 > New Revision: 303076 > URL: https://svnweb.freebsd.org/changeset/base/303076 > > Log: > vesa: fix panic on suspend > > Fix the following panic seen when migrating a FreeBSD guest on Xen: > > panic: mtx_lock() of destroyed mutex @ /usr/src/sys/dev/fb/vesa.c:541 > cpuid = 0 > KDB: stack backtrace: > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe001d2fa4f0 > vpanic() at vpanic+0x182/frame 0xfffffe001d2fa570 > kassert_panic() at kassert_panic+0x126/frame 0xfffffe001d2fa5e0 > __mtx_lock_flags() at __mtx_lock_flags+0x15b/frame 0xfffffe001d2fa630 > vesa_bios_save_restore() at vesa_bios_save_restore+0x78/frame 0xfffffe001d2fa680 > vga_suspend() at vga_suspend+0xa3/frame 0xfffffe001d2fa6b0 > isavga_suspend() at isavga_suspend+0x1d/frame 0xfffffe001d2fa6d0 > bus_generic_suspend_child() at bus_generic_suspend_child+0x44/frame > [...] > > This is caused because vga_sub_configure (which is called if the VGA adapter > is attached after VESA tried to initialize), points to vesa_configure, which > doesn't initialize the VESA mutex. In order to fix it, make sure > vga_sub_configure points to vesa_load, so that all the needed vesa > components are properly initialized. This panics a box without VESA (a dumb VGA) since vesa_init_done doesn't get set to true if VESA fails to find anything during its probe, so the mutex can be initialized twice. I think it is better to just revert this change and use MTX_SYSINIT to initialize the mutex instead. vga0: <Generic ISA VGA> at port 0x3d0-0x3db iomem 0xb8000-0xbffff on isa0 panic: lock "VESA lock" 0xffffffff81c64af0 already initialized cpuid = 0 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xffffffff824ec7a0 kdb_backtrace() at kdb_backtrace+0x39/frame 0xffffffff824ec850 vpanic() at vpanic+0x181/frame 0xffffffff824ec8d0 kassert_panic() at kassert_panic+0x17d/frame 0xffffffff824ec960 lock_init() at lock_init+0x186/frame 0xffffffff824ec9a0 _mtx_init() at _mtx_init+0x90/frame 0xffffffff824ec9e0 vesa_late_load() at vesa_late_load+0x2d/frame 0xffffffff824eca00 vga_init() at vga_init+0x65/frame 0xffffffff824eca20 vga_attach_unit() at vga_attach_unit+0x4b/frame 0xffffffff824eca50 isavga_attach() at isavga_attach+0x6c/frame 0xffffffff824eca90 DEVICE_ATTACH() at DEVICE_ATTACH+0x44/frame 0xffffffff824ecab0 https://reviews.freebsd.org/D7290 is a suggested patch that works in my test case. -- John Baldwin
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