Messages in this thread |  | | | Date | Tue, 27 May 2008 09:51:04 +0200 | | From | "Zdenek Kabelac" <> | | Subject | vmalloc problem with DEBUG_PAGEALLOC config option |
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Hello
Recently I've spent some time with hunting weird problem which appeared to be caused by the CONFIG_DEBUG_PAGEALLOC option. After the crash of 'nash' sometimes my application started to behave strange - after some debugging and testing when I've basically tried everything else :) because it wouldn't come to my mind what could be wrong I' ve noticed, that inside the kernel driver 'vmalloc-ated' memory chunk simply doesn't get the right memory copy from the funtion call copy_from_user(). When I want to get 16kb copied from user space and I prefil it with some byte pattern, I get zeroed area. When I use 'get_user()' I see correct user-space data - so the problem is with the copying and DEBUG_PAGEALLOC enabled.
When I'm not using this debug option - I'm not able to replicate my problem with copy_from_user().
I'm using 64bit x86 kernel on 2GB T61
Zdenek
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