[linuxsh-dev] "pte_clear" needed in copy_user_page? (was Re: System reset while INIT processing)

[Masahiro A. <m-...@aa...>]

Sugioka-san, Niibe-san and all,

Current arch/sh/mm/cache.c in CVS gives me Oops error on our custom
board, while INIT. (This doesn't happen on SolutionEngine 7750S.)

Errors are "Unable to handle kernel paging request at virtual address
c0000000", with address varies to c0001000/c0002000/c0003000. Errors
occur at PC=8800c488, which is within __flush_dcache_region.

copy_user_page and clear_user_page were modified to call pte_clear after
copy_page/clear_page. If I comment this call out, then Oops errors
disappear. (In fact, after comment out, the system is so stable so far
that RTLinux is running reliably.)

I still don't understand the reason of call to it, but I would like to
know if it is necessary to call it or not. If it is, then what do you
think I should do to kill this Oops error?

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Masahiro ABE, A&D Co., Ltd. Japan