diff options
authorTrent Piepho <>2006-05-15 09:44:06 -0700
committerLinus Torvalds <>2006-05-15 11:20:55 -0700
commit5e376613899076396d0c97de67ad072587267370 (patch)
parent0159677857c5ada0a0a2c03a4dd59312382b73d0 (diff)
[PATCH] symbol_put_addr() locks kernel
Even since a previous patch: Fix race between CONFIG_DEBUG_SLABALLOC and modules Sun, 27 Jun 2004 17:55:19 +0000 (17:55 +0000);a=commit;h=92b3db26d31cf21b70e3c1eadc56c179506d8fbe The function symbol_put_addr() will deadlock the kernel. symbol_put_addr() would acquire modlist_lock, then while holding the lock call two functions kernel_text_address() and module_text_address() which also try to acquire the same lock. This deadlocks the kernel of course. This patch changes symbol_put_addr() to not acquire the modlist_lock, it doesn't need it since it never looks at the module list directly. Also, it now uses core_kernel_text() instead of kernel_text_address(). The latter has an additional check for addr inside a module, but we don't need to do that since we call module_text_address() (the same function kernel_text_address uses) ourselves. Signed-off-by: Trent Piepho <> Cc: Zwane Mwaikambo <> Acked-by: Rusty Russell <> Cc: Johannes Stezenbach <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
3 files changed, 8 insertions, 7 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index e1bd0842f6a1..f4fc576ed4c4 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -124,6 +124,7 @@ extern int get_option(char **str, int *pint);
extern char *get_options(const char *str, int nints, int *ints);
extern unsigned long long memparse(char *ptr, char **retptr);
+extern int core_kernel_text(unsigned long addr);
extern int __kernel_text_address(unsigned long addr);
extern int kernel_text_address(unsigned long addr);
extern int session_of_pgrp(int pgrp);
diff --git a/kernel/extable.c b/kernel/extable.c
index 7501b531ceed..7fe262855317 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -40,7 +40,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
return e;
-static int core_kernel_text(unsigned long addr)
+int core_kernel_text(unsigned long addr)
if (addr >= (unsigned long)_stext &&
addr <= (unsigned long)_etext)
diff --git a/kernel/module.c b/kernel/module.c
index d24deb0dbbc9..bbe04862e1b0 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -705,14 +705,14 @@ EXPORT_SYMBOL(__symbol_put);
void symbol_put_addr(void *addr)
- unsigned long flags;
+ struct module *modaddr;
- spin_lock_irqsave(&modlist_lock, flags);
- if (!kernel_text_address((unsigned long)addr))
- BUG();
+ if (core_kernel_text((unsigned long)addr))
+ return;
- module_put(module_text_address((unsigned long)addr));
- spin_unlock_irqrestore(&modlist_lock, flags);
+ if (!(modaddr = module_text_address((unsigned long)addr)))
+ BUG();
+ module_put(modaddr);