Date: Sun, 9 Jun 2002 17:39:18 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Arun Sharma <arun@sharma-home.net> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: 0xdeadxxxx ? Message-ID: <200206100039.g5A0dIRr004783@apollo.backplane.com> References: <20020610002316.GA6628@sharma-home.net>
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For debugging purposes kernel memory which has been freed is filled with the pattern 0xdeadc0de (hex). So if you get a VM fault on something similar then something in the system has tried to reference a structure that is sitting in memory which has been freed. A no-no to be sure :-). 0xdeadc162 - 0xdeadc0de would be the structural offset relative to the pointer. The pointer itself is probably sitting at 0xdeadc0de. -Matt Matthew Dillon <dillon@backplane.com> :I just got a kernel mode page fault. I'd like to find out more :about : :> fault virtual address = 0xdeadc162 : :It looks like the address is meant to signal a particular class of :error. Which one ? : : -Arun : :Background fsck: : :Fatal trap 12: page fault while in kernel mode :cpuid = 0; lapic.id = 00000000 :fault virtual address = 0xdeadc162 :fault code = supervisor read, page not present :instruction pointer = 0x8:0xc0277ebe :stack pointer = 0x10:0xcaee688c :frame pointer = 0x10:0xcaee68b0 :code segment = base 0x0, limit 0xfffff, type 0x1b : = DPL 0, pres 1, def32 1, gran 1 :processor eflags = interrupt enabled, resume, IOPL = 0 :current process = 343 (cron) :kernel: type 12 trap, code=0 :Stopped at ufs_strategy+0xbc: calll *0(%edx,%eax,4) :db> trace :ufs_strategy(caee68e4,caee6900,c01e7a1a,caee68e4,0) at ufs_strategy+0xbc :ufs_vnoperate(caee68e4) at ufs_vnoperate+0x13 :breadn(cacdbb00,0,0,400,0) at breadn+0xc4 :bread(cacdbb00,0,0,400,0) at bread+0x20 :ffs_blkatoff(cacdbb00,0,0,0,caee69c8) at ffs_blkatoff+0x88 :ufs_lookup(caee6af0,caee6b2c,c01ebe61,caee6af0,caaca274) at :ufs_lookup+0x31f :ufs_vnoperate(caee6af0) at ufs_vnoperate+0x13 :vfs_cache_lookup(caee6b94,caee6bc0,c01efc94,caee6b94,caeb841c) at :vfs_cache_loo9 :ufs_vnoperate(caee6b94) at ufs_vnoperate+0x13 :lookup(caee6c30,caeb841c,caee6bec,c01ce890,c0364178) at lookup+0x2b2 :namei(caee6c30) at namei+0x1df :lstat(caeb841c,caee6d14,2,2,292) at lstat+0x4a :syscall(2f,2f,2f,0,0) at syscall+0x1db :syscall_with_err_pushed() at syscall_with_err_pushed+0x1b :--- syscall (190, FreeBSD ELF, lstat), eip = 0x280b2f33, esp = 0xbfbff1ec, ebp - To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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