diff options
author | Ingo Molnar <mingo@elte.hu> | 2009-07-01 09:43:53 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-01 10:26:23 -0700 |
commit | 57d81f6f393b245894ca0cd828f80ce7e3294f39 (patch) | |
tree | e825b033d86bf42e768c645cb66201a94cd7a354 | |
parent | e83c2b0ff325f52dda1aff3572d0e1516216c54b (diff) | |
download | linux-57d81f6f393b245894ca0cd828f80ce7e3294f39.tar.gz linux-57d81f6f393b245894ca0cd828f80ce7e3294f39.tar.bz2 linux-57d81f6f393b245894ca0cd828f80ce7e3294f39.zip |
kmemleak: Fix scheduling-while-atomic bug
One of the kmemleak changes caused the following
scheduling-while-holding-the-tasklist-lock regression on x86:
BUG: sleeping function called from invalid context at mm/kmemleak.c:795
in_atomic(): 1, irqs_disabled(): 0, pid: 1737, name: kmemleak
2 locks held by kmemleak/1737:
#0: (scan_mutex){......}, at: [<c10c4376>] kmemleak_scan_thread+0x45/0x86
#1: (tasklist_lock){......}, at: [<c10c3bb4>] kmemleak_scan+0x1a9/0x39c
Pid: 1737, comm: kmemleak Not tainted 2.6.31-rc1-tip #59266
Call Trace:
[<c105ac0f>] ? __debug_show_held_locks+0x1e/0x20
[<c102e490>] __might_sleep+0x10a/0x111
[<c10c38d5>] scan_yield+0x17/0x3b
[<c10c3970>] scan_block+0x39/0xd4
[<c10c3bc6>] kmemleak_scan+0x1bb/0x39c
[<c10c4331>] ? kmemleak_scan_thread+0x0/0x86
[<c10c437b>] kmemleak_scan_thread+0x4a/0x86
[<c104d73e>] kthread+0x6e/0x73
[<c104d6d0>] ? kthread+0x0/0x73
[<c100959f>] kernel_thread_helper+0x7/0x10
kmemleak: 834 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
The bit causing it is highly dubious:
static void scan_yield(void)
{
might_sleep();
if (time_is_before_eq_jiffies(next_scan_yield)) {
schedule();
next_scan_yield = jiffies + jiffies_scan_yield;
}
}
It called deep inside the codepath and in a conditional way,
and that is what crapped up when one of the new scan_block()
uses grew a tasklist_lock dependency.
This minimal patch removes that yielding stuff and adds the
proper cond_resched().
The background scanning thread could probably also be reniced
to +10.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | mm/kmemleak.c | 31 |
1 files changed, 1 insertions, 30 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index eeece2deace2..e766e1da09d2 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -105,7 +105,6 @@ #define MAX_TRACE 16 /* stack trace length */ #define REPORTS_NR 50 /* maximum number of reported leaks */ #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ -#define MSECS_SCAN_YIELD 10 /* CPU yielding period */ #define SECS_FIRST_SCAN 60 /* delay before the first scan */ #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */ @@ -186,10 +185,7 @@ static atomic_t kmemleak_error = ATOMIC_INIT(0); static unsigned long min_addr = ULONG_MAX; static unsigned long max_addr; -/* used for yielding the CPU to other tasks during scanning */ -static unsigned long next_scan_yield; static struct task_struct *scan_thread; -static unsigned long jiffies_scan_yield; /* used to avoid reporting of recently allocated objects */ static unsigned long jiffies_min_age; static unsigned long jiffies_last_scan; @@ -786,21 +782,6 @@ void kmemleak_no_scan(const void *ptr) EXPORT_SYMBOL(kmemleak_no_scan); /* - * Yield the CPU so that other tasks get a chance to run. The yielding is - * rate-limited to avoid excessive number of calls to the schedule() function - * during memory scanning. - */ -static void scan_yield(void) -{ - might_sleep(); - - if (time_is_before_eq_jiffies(next_scan_yield)) { - schedule(); - next_scan_yield = jiffies + jiffies_scan_yield; - } -} - -/* * Memory scanning is a long process and it needs to be interruptable. This * function checks whether such interrupt condition occured. */ @@ -840,15 +821,6 @@ static void scan_block(void *_start, void *_end, if (scan_should_stop()) break; - /* - * When scanning a memory block with a corresponding - * kmemleak_object, the CPU yielding is handled in the calling - * code since it holds the object->lock to avoid the block - * freeing. - */ - if (!scanned) - scan_yield(); - object = find_and_get_object(pointer, 1); if (!object) continue; @@ -1014,7 +986,7 @@ static void kmemleak_scan(void) */ object = list_entry(gray_list.next, typeof(*object), gray_list); while (&object->gray_list != &gray_list) { - scan_yield(); + cond_resched(); /* may add new objects to the list */ if (!scan_should_stop()) @@ -1385,7 +1357,6 @@ void __init kmemleak_init(void) int i; unsigned long flags; - jiffies_scan_yield = msecs_to_jiffies(MSECS_SCAN_YIELD); jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE); jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000); |