Messages in this thread | | | Date | Mon, 24 Feb 1997 18:10:50 -0500 (EST) | From | Ion Badulescu <> | Subject | Re: Unable to handle kernel paging request [ext2 problem] |
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On Mon, 24 Feb 1997, Ion Badulescu wrote:
> Really, folks, can you try out Bernd's code and see if it oopses on your > particular configuration? Please? :) Drop me a message if you got rid of > the message and I'll forward it to you.
Follow-up on my own message:
1. the problem only occurs if core is dumped (my tests had been done with ulimit -c0 initially) 2. the 2.1.26 kernel catches an exception in ext2_file_write when running the same code, so we definitely have a problem there. (this could also explain some weird exceptions other people got in their logs) 3. the function which generates the oops is memcpy_fromfs, when it dereferences the buf pointer. buf is not touched at all inside ext2_file_write; also, there is no verify_area before the memcpy_fromfs call 4. I got stack traces with do_truncate as well as __brelse as the next return addresses on the stack, however neither of these two functions call ext2_file_write directly:
do_truncate: call vmtruncate __brelse : call refile_buffer
From Jon's stack dump it would appear that the bogus value for buf is passed by some higher-up function, but it doesn't appear at all in my own stack dump:
Feb 24 17:52:09 moisil kernel: Unable to handle kernel paging request at virtual address 40007000 [...] Feb 24 17:52:09 moisil kernel: Stack: 00001000 0000000a 00001000 0003f000 00000000 00000000 001a55f8 00000000 Feb 24 17:52:09 moisil kernel: 00000000 00000010 00004000 00000000 021a7e9c 00000000 0000010c 0271c68c Feb 24 17:52:09 moisil kernel: 0271c5d0 0000000c 0271c688 0271c5d0 0271c5d0 00000000 00000000 021edd4c
Any ideas? Is some ext2 guru willing to look into this? :)
Ionut
-- It is better to keep your mouth shut and be thought a fool, than to open it and remove all doubt.
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