Messages in this thread | | | From | Keith Owens <> | Subject | Re: [PATCH][RFC] __init and friends support for loadable modules | Date | Thu, 09 May 2002 00:02:07 +1000 |
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On Wed, 8 May 2002 14:29:33 +0400, Andrey Panin <pazke@orbita1.ru> wrote: >attached patch adds support for freeing .init sections of loadable modules >after init_module() function exits. Modutils have support for this since 19= >98, >but kernel support didn't exist.
The main reason I have not done this myself is the interaction between freeing code areas and the exception and unwind tables. When you free code, you should remove or nullify the related unwind and exception entries. Another module could be loaded into the area that used to contain init code and it would then be mapped by the first module's tables, oops.
Fixing exception tables is relatively easy, search_exception_table() can check if the address fits within the module (taking runsize into account) before running the exception table. Unwind data is harder, it is all architecture specific. Your patch will not be complete without fixing all tables that point at module code. Don't forget the MIPS DBE table.
Rusty and I plan to completely redo module loading and unloading and the corresponding modutils support in 2.5. That will (hopefully) include additional features such as per-node replication of pure module areas for NUMA boxes. For me, the ability to free .init text and data from modules falls into the category of "would be nice but the gain is not worth the bother just for 2.4".
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