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Commit [533637] Maximize Restore History

modules: Fix module_bug_list list corruption race

With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.

However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling. That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.

Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.

So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.

Future fixups:
- move the module list handling code into kernel/module.c where it
belongs.
- get rid of 'module_bug_list' and just use the regular list of modules
(called 'modules' - imagine that) that we already create and maintain
for other reasons.

Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Linus Torvalds Linus Torvalds 2010-10-05

changed arch/avr32/kernel/module.c
changed arch/h8300/kernel/module.c
changed arch/mn10300/kernel/module.c
changed arch/parisc/kernel/module.c
changed arch/powerpc/kernel/module.c
changed arch/s390/kernel/module.c
changed arch/sh/kernel/module.c
changed arch/x86/kernel/module.c
changed include/linux/module.h
changed kernel/module.c
changed lib/bug.c
arch/avr32/kernel/module.c Diff Switch to side-by-side view
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arch/h8300/kernel/module.c Diff Switch to side-by-side view
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arch/mn10300/kernel/module.c Diff Switch to side-by-side view
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arch/parisc/kernel/module.c Diff Switch to side-by-side view
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arch/powerpc/kernel/module.c Diff Switch to side-by-side view
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arch/s390/kernel/module.c Diff Switch to side-by-side view
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arch/sh/kernel/module.c Diff Switch to side-by-side view
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arch/x86/kernel/module.c Diff Switch to side-by-side view
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include/linux/module.h Diff Switch to side-by-side view
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kernel/module.c Diff Switch to side-by-side view
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lib/bug.c Diff Switch to side-by-side view
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