Date: Wed, 28 Jan 2015 22:33:15 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: current@FreeBSD.org Subject: Re: panic in softdep_slowdown() Message-ID: <20150128193315.GC15484@glebius.int.ru> In-Reply-To: <20150128190441.GO42409@kib.kiev.ua> References: <20150127203103.GZ15484@glebius.int.ru> <20150128104842.GL42409@kib.kiev.ua> <20150128182230.GB15484@glebius.int.ru> <20150128190441.GO42409@kib.kiev.ua>
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On Wed, Jan 28, 2015 at 09:04:42PM +0200, Konstantin Belousov wrote: K> > I can't see where integer divide fault can happen with stat_flush_threads=1 :( K> K> Look at the exact asm instruction which faulted, also look at the registers K> content. K> K> It might be hypervisor bug, after all. Yes, for me it looks like it. %edx should be one as well as -0x44(%rbp). 0xffffffff80895d43 <softdep_slowdown+435>: mov -0x20(%rbp),%ecx 0xffffffff80895d46 <softdep_slowdown+438>: mov %ecx,%edx 0xffffffff80895d48 <softdep_slowdown+440>: shr $0x1f,%edx 0xffffffff80895d4b <softdep_slowdown+443>: add %edx,%ecx 0xffffffff80895d4d <softdep_slowdown+445>: sar %ecx 0xffffffff80895d4f <softdep_slowdown+447>: mov 0xffffffff80ee24c8,%edx 0xffffffff80895d56 <softdep_slowdown+454>: mov %rax,-0x40(%rbp) 0xffffffff80895d5a <softdep_slowdown+458>: mov %ecx,%eax 0xffffffff80895d5c <softdep_slowdown+460>: mov %edx,-0x44(%rbp) 0xffffffff80895d5f <softdep_slowdown+463>: cltd 0xffffffff80895d60 <softdep_slowdown+464>: mov -0x44(%rbp),%ecx 0xffffffff80895d63 <softdep_slowdown+467>: idiv %ecx (kgdb) p &stat_flush_threads $5 = (int *) 0xffffffff80ee24c8 (kgdb) info registers rax 0x12b86 76678 rbx 0x4 4 rcx 0x0 0 rdx 0x0 0 rsi 0x3e8 1000 rdi 0x99 153 rbp 0xfffffe001eb5f2b0 0xfffffe001eb5f2b0 ... (kgdb) p *(int *)($rbp - 0x44) $4 = 0 (kgdb) p *(int *)($rbp - 0x40) $8 = 0 (kgdb) p &max_softdeps_hard $11 = (int *) 0xfffffe001eb5f290 (kgdb) p (int *)($rbp - 0x20) $12 = (int *) 0xfffffe001eb5f290 (kgdb) p max_softdeps_hard $10 = 153357 -- Totus tuus, Glebius.
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