From cf40bd16fdad42c053040bcd3988f5fdedbb6c57 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 21 Jan 2009 08:12:39 +0100 Subject: lockdep: annotate reclaim context (__GFP_NOFS) Here is another version, with the incremental patch rolled up, and added reclaim context annotation to kswapd, and allocation tracing to slab allocators (which may only ever reach the page allocator in rare cases, so it is good to put annotations here too). Haven't tested this version as such, but it should be getting closer to merge worthy ;) -- After noticing some code in mm/filemap.c accidentally perform a __GFP_FS allocation when it should not have been, I thought it might be a good idea to try to catch this kind of thing with lockdep. I coded up a little idea that seems to work. Unfortunately the system has to actually be in __GFP_FS page reclaim, then take the lock, before it will mark it. But at least that might still be some orders of magnitude more common (and more debuggable) than an actual deadlock condition, so we have some improvement I hope (the concept is no less complete than discovery of a lock's interrupt contexts). I guess we could even do the same thing with __GFP_IO (normal reclaim), and even GFP_NOIO locks too... but filesystems will have the most locks and fiddly code paths, so let's start there and see how it goes. It *seems* to work. I did a quick test. ================================= [ INFO: inconsistent lock state ] 2.6.28-rc6-00007-ged31348-dirty #26 --------------------------------- inconsistent {in-reclaim-W} -> {ov-reclaim-W} usage. modprobe/8526 [HC0[0]:SC0[0]:HE1:SE1] takes: (testlock){--..}, at: [] brd_init+0x55/0x216 [brd] {in-reclaim-W} state was registered at: [] __lock_acquire+0x75b/0x1a60 [] lock_acquire+0x91/0xc0 [] mutex_lock_nested+0xb1/0x310 [] brd_init+0x2b/0x216 [brd] [] _stext+0x3b/0x170 [] sys_init_module+0xaf/0x1e0 [] system_call_fastpath+0x16/0x1b [] 0xffffffffffffffff irq event stamp: 3929 hardirqs last enabled at (3929): [] mutex_lock_nested+0x285/0x310 hardirqs last disabled at (3928): [] mutex_lock_nested+0x59/0x310 softirqs last enabled at (3732): [] sk_filter+0x83/0xe0 softirqs last disabled at (3730): [] sk_filter+0x16/0xe0 other info that might help us debug this: 1 lock held by modprobe/8526: #0: (testlock){--..}, at: [] brd_init+0x55/0x216 [brd] stack backtrace: Pid: 8526, comm: modprobe Not tainted 2.6.28-rc6-00007-ged31348-dirty #26 Call Trace: [] print_usage_bug+0x193/0x1d0 [] mark_lock+0xaf0/0xca0 [] mark_held_locks+0x55/0xc0 [] ? brd_init+0x0/0x216 [brd] [] trace_reclaim_fs+0x2a/0x60 [] __alloc_pages_internal+0x475/0x580 [] ? mutex_lock_nested+0x26e/0x310 [] ? brd_init+0x0/0x216 [brd] [] brd_init+0x6a/0x216 [brd] [] ? brd_init+0x0/0x216 [brd] [] _stext+0x3b/0x170 [] ? mutex_unlock+0x9/0x10 [] ? __mutex_unlock_slowpath+0x10d/0x180 [] ? trace_hardirqs_on_caller+0x12c/0x190 [] sys_init_module+0xaf/0x1e0 [] system_call_fastpath+0x16/0x1b Signed-off-by: Nick Piggin Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/lockdep_proc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/lockdep_proc.c') diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index 13716b813896..b84a1dfa9077 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -84,7 +84,7 @@ static int l_show(struct seq_file *m, void *v) { struct lock_class *class = v; struct lock_list *entry; - char c1, c2, c3, c4; + char c1, c2, c3, c4, c5, c6; if (v == SEQ_START_TOKEN) { seq_printf(m, "all lock classes:\n"); @@ -100,8 +100,8 @@ static int l_show(struct seq_file *m, void *v) seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class)); #endif - get_usage_chars(class, &c1, &c2, &c3, &c4); - seq_printf(m, " %c%c%c%c", c1, c2, c3, c4); + get_usage_chars(class, &c1, &c2, &c3, &c4, &c5, &c6); + seq_printf(m, " %c%c%c%c%c%c", c1, c2, c3, c4, c5, c6); seq_printf(m, ": "); print_name(m, class); -- cgit v1.2.2 From 4fc95e867f1e75351b89db3c68212dfcce7ea563 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 22 Jan 2009 13:10:52 +0100 Subject: lockdep: sanitize bit names s/\(LOCKF\?_ENABLED_[^ ]*\)S\(_READ\)\?\>/\1\2/g So that the USED_IN and ENABLED have the same names. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/lockdep_proc.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'kernel/lockdep_proc.c') diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index b84a1dfa9077..bd474fd9df9d 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -300,27 +300,27 @@ static int lockdep_stats_show(struct seq_file *m, void *v) nr_uncategorized++; if (class->usage_mask & LOCKF_USED_IN_IRQ) nr_irq_safe++; - if (class->usage_mask & LOCKF_ENABLED_IRQS) + if (class->usage_mask & LOCKF_ENABLED_IRQ) nr_irq_unsafe++; if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) nr_softirq_safe++; - if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS) + if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ) nr_softirq_unsafe++; if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) nr_hardirq_safe++; - if (class->usage_mask & LOCKF_ENABLED_HARDIRQS) + if (class->usage_mask & LOCKF_ENABLED_HARDIRQ) nr_hardirq_unsafe++; if (class->usage_mask & LOCKF_USED_IN_IRQ_READ) nr_irq_read_safe++; - if (class->usage_mask & LOCKF_ENABLED_IRQS_READ) + if (class->usage_mask & LOCKF_ENABLED_IRQ_READ) nr_irq_read_unsafe++; if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) nr_softirq_read_safe++; - if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ) + if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ) nr_softirq_read_unsafe++; if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) nr_hardirq_read_safe++; - if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ) + if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ) nr_hardirq_read_unsafe++; #ifdef CONFIG_PROVE_LOCKING -- cgit v1.2.2 From f510b233cfc7bfd57b6007071c52aa42e3d16b06 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 22 Jan 2009 17:53:47 +0100 Subject: lockdep: get_user_chars() redo Generic, states independent, get_user_chars(). Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/lockdep_proc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/lockdep_proc.c') diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index bd474fd9df9d..b51064ce564a 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -84,7 +84,7 @@ static int l_show(struct seq_file *m, void *v) { struct lock_class *class = v; struct lock_list *entry; - char c1, c2, c3, c4, c5, c6; + char usage[LOCK_USAGE_CHARS]; if (v == SEQ_START_TOKEN) { seq_printf(m, "all lock classes:\n"); @@ -100,8 +100,8 @@ static int l_show(struct seq_file *m, void *v) seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class)); #endif - get_usage_chars(class, &c1, &c2, &c3, &c4, &c5, &c6); - seq_printf(m, " %c%c%c%c%c%c", c1, c2, c3, c4, c5, c6); + get_usage_chars(class, usage); + seq_printf(m, " %s", usage); seq_printf(m, ": "); print_name(m, class); -- cgit v1.2.2 From 9833f8cb952b9aa3f98a71e7bef8820cee3261a0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Sat, 14 Feb 2009 16:59:04 +0100 Subject: lockstat: warn about disabled lock debugging Avoid confusion and clearly state lock debugging got disabled. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/lockdep_proc.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/lockdep_proc.c') diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index b51064ce564a..d7135aa2d2c4 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -601,6 +601,10 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) static void seq_header(struct seq_file *m) { seq_printf(m, "lock_stat version 0.3\n"); + + if (unlikely(!debug_locks)) + seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n"); + seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1)); seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s " "%14s %14s\n", -- cgit v1.2.2