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Subject[patch 10/11] mutex subsystem, more debugging code
more mutex debugging: check for held locks during memory freeing,
task exit, enable sysrq printouts, etc.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>

----

arch/i386/mm/pageattr.c | 4 ++++
drivers/char/sysrq.c | 19 +++++++++++++++++++
include/linux/mm.h | 4 ++++
kernel/exit.c | 5 +++++
kernel/sched.c | 1 +
mm/page_alloc.c | 3 +++
mm/slab.c | 1 +
7 files changed, 37 insertions(+)

Index: linux/arch/i386/mm/pageattr.c
===================================================================
--- linux.orig/arch/i386/mm/pageattr.c
+++ linux/arch/i386/mm/pageattr.c
@@ -207,6 +207,10 @@ void kernel_map_pages(struct page *page,
{
if (PageHighMem(page))
return;
+ if (!enable)
+ mutex_debug_check_no_locks_freed(page_address(page),
+ page_address(page+numpages));
+
/* the return value is ignored - the calls cannot fail,
* large pages are disabled at boot time.
*/
Index: linux/drivers/char/sysrq.c
===================================================================
--- linux.orig/drivers/char/sysrq.c
+++ linux/drivers/char/sysrq.c
@@ -153,6 +153,21 @@ static struct sysrq_key_op sysrq_mountro

/* END SYNC SYSRQ HANDLERS BLOCK */

+#ifdef CONFIG_DEBUG_MUTEXES
+
+static void
+sysrq_handle_showlocks(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
+{
+ mutex_debug_show_all_locks();
+}
+
+static struct sysrq_key_op sysrq_showlocks_op = {
+ .handler = sysrq_handle_showlocks,
+ .help_msg = "show-all-locks(D)",
+ .action_msg = "Show Locks Held",
+};
+
+#endif

/* SHOW SYSRQ HANDLERS BLOCK */

@@ -294,7 +309,11 @@ static struct sysrq_key_op *sysrq_key_ta
#else
/* c */ NULL,
#endif
+#ifdef CONFIG_DEBUG_MUTEXES
+/* d */ &sysrq_showlocks_op,
+#else
/* d */ NULL,
+#endif
/* e */ &sysrq_term_op,
/* f */ &sysrq_moom_op,
/* g */ NULL,
Index: linux/include/linux/mm.h
===================================================================
--- linux.orig/include/linux/mm.h
+++ linux/include/linux/mm.h
@@ -13,6 +13,7 @@
#include <linux/rbtree.h>
#include <linux/prio_tree.h>
#include <linux/fs.h>
+#include <linux/mutex.h>

struct mempolicy;
struct anon_vma;
@@ -977,6 +978,9 @@ static inline void vm_stat_account(struc
static inline void
kernel_map_pages(struct page *page, int numpages, int enable)
{
+ if (!PageHighMem(page) && !enable)
+ mutex_debug_check_no_locks_freed(page_address(page),
+ page_address(page + numpages));
}
#endif

Index: linux/kernel/exit.c
===================================================================
--- linux.orig/kernel/exit.c
+++ linux/kernel/exit.c
@@ -29,6 +29,7 @@
#include <linux/syscalls.h>
#include <linux/signal.h>
#include <linux/cn_proc.h>
+#include <linux/mutex.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -870,6 +871,10 @@ fastcall NORET_TYPE void do_exit(long co
mpol_free(tsk->mempolicy);
tsk->mempolicy = NULL;
#endif
+ /*
+ * If DEBUG_MUTEXES is on, make sure we are holding no locks:
+ */
+ mutex_debug_check_no_locks_held(tsk);

/* PF_DEAD causes final put_task_struct after we schedule. */
preempt_disable();
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -4379,6 +4379,7 @@ void show_state(void)
} while_each_thread(g, p);

read_unlock(&tasklist_lock);
+ mutex_debug_show_all_locks();
}

/**
Index: linux/mm/page_alloc.c
===================================================================
--- linux.orig/mm/page_alloc.c
+++ linux/mm/page_alloc.c
@@ -400,6 +400,9 @@ void __free_pages_ok(struct page *page,
int reserved = 0;

arch_free_page(page, order);
+ if (!PageHighMem(page))
+ mutex_debug_check_no_locks_freed(page_address(page),
+ page_address(page+(1<<order)));

#ifndef CONFIG_MMU
if (order > 0)
Index: linux/mm/slab.c
===================================================================
--- linux.orig/mm/slab.c
+++ linux/mm/slab.c
@@ -3038,6 +3038,7 @@ void kfree(const void *objp)
local_irq_save(flags);
kfree_debugcheck(objp);
c = page_get_cache(virt_to_page(objp));
+ mutex_debug_check_no_locks_freed(objp, objp+obj_reallen(c));
__cache_free(c, (void*)objp);
local_irq_restore(flags);
}
-
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