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 --- mm/page_alloc.c | 5 +++++ mm/slab.c | 4 ++++ mm/slob.c | 2 ++ mm/slub.c | 1 + mm/vmscan.c | 3 +++ 5 files changed, 15 insertions(+) (limited to 'mm') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5675b3073854..22b15a4cde8a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1479,6 +1479,8 @@ __alloc_pages_internal(gfp_t gfp_mask, unsigned int order, unsigned long did_some_progress; unsigned long pages_reclaimed = 0; + lockdep_trace_alloc(gfp_mask); + might_sleep_if(wait); if (should_fail_alloc_page(gfp_mask, order)) @@ -1578,12 +1580,15 @@ nofail_alloc: */ cpuset_update_task_memory_state(); p->flags |= PF_MEMALLOC; + + lockdep_set_current_reclaim_state(gfp_mask); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state; did_some_progress = try_to_free_pages(zonelist, order, gfp_mask); p->reclaim_state = NULL; + lockdep_clear_current_reclaim_state(); p->flags &= ~PF_MEMALLOC; cond_resched(); diff --git a/mm/slab.c b/mm/slab.c index ddc41f337d58..6b61de8543ec 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3318,6 +3318,8 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, unsigned long save_flags; void *ptr; + lockdep_trace_alloc(flags); + if (slab_should_failslab(cachep, flags)) return NULL; @@ -3394,6 +3396,8 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller) unsigned long save_flags; void *objp; + lockdep_trace_alloc(flags); + if (slab_should_failslab(cachep, flags)) return NULL; diff --git a/mm/slob.c b/mm/slob.c index bf7e8fc3aed8..1264799df5d1 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -464,6 +464,8 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node) unsigned int *m; int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); + lockdep_trace_alloc(flags); + if (size < PAGE_SIZE - align) { if (!size) return ZERO_SIZE_PTR; diff --git a/mm/slub.c b/mm/slub.c index bdc9abb08a23..214eb207c513 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1596,6 +1596,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s, unsigned long flags; unsigned int objsize; + lockdep_trace_alloc(gfpflags); might_sleep_if(gfpflags & __GFP_WAIT); if (should_failslab(s->objsize, gfpflags)) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9a27c44aa327..303eb658b50b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1963,6 +1963,9 @@ static int kswapd(void *p) struct reclaim_state reclaim_state = { .reclaimed_slab = 0, }; + + lockdep_set_current_reclaim_state(GFP_KERNEL); + node_to_cpumask_ptr(cpumask, pgdat->node_id); if (!cpumask_empty(cpumask)) -- cgit v1.2.3-59-g8ed1b From 6700ec65c207068a81a535e9dca616fefac21671 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 15 Feb 2009 21:18:17 +0100 Subject: lockdep: annotate reclaim context (__GFP_NOFS), fix MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Impact: fix build warning Fix: mm/vmscan.c: In function ‘kswapd’: mm/vmscan.c:1969: warning: ISO C90 forbids mixed declarations and code node_to_cpumask_ptr(cpumask, pgdat->node_id), has a side-effect: it defines the 'cpumask' local variable as well, so it has to go into the variable definition section. Sidenote: it might make sense to make this purpose of these macros more apparent, by naming them the standard way, such as: DEFINE_node_to_cpumask_ptr(cpumask, pgdat->node_id); (But that is outside the scope of this patch.) Cc: Rusty Russell Cc: Mike Travis Cc: Andrew Morton Cc: Nick Piggin Signed-off-by: Ingo Molnar --- mm/vmscan.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 303eb658b50b..cf8441345277 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1963,11 +1963,10 @@ static int kswapd(void *p) struct reclaim_state reclaim_state = { .reclaimed_slab = 0, }; + node_to_cpumask_ptr(cpumask, pgdat->node_id); lockdep_set_current_reclaim_state(GFP_KERNEL); - node_to_cpumask_ptr(cpumask, pgdat->node_id); - if (!cpumask_empty(cpumask)) set_cpus_allowed_ptr(tsk, cpumask); current->reclaim_state = &reclaim_state; -- cgit v1.2.3-59-g8ed1b From 19cefdffbfe0f7e280f21e80875937e8700e99e2 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 15 Mar 2009 06:03:11 +0100 Subject: lockdep: annotate reclaim context (__GFP_NOFS), fix SLOB MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Impact: build fix fix typo in mm/slob.c: mm/slob.c:469: error: ‘flags’ undeclared (first use in this function) mm/slob.c:469: error: (Each undeclared identifier is reported only once mm/slob.c:469: error: for each function it appears in.) Cc: Nick Piggin Cc: Peter Zijlstra LKML-Reference: <20090128135457.350751756@chello.nl> Signed-off-by: Ingo Molnar --- mm/slob.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/slob.c b/mm/slob.c index 1264799df5d1..4b1c0c1d63cb 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -464,7 +464,7 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node) unsigned int *m; int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); - lockdep_trace_alloc(flags); + lockdep_trace_alloc(gfp); if (size < PAGE_SIZE - align) { if (!size) -- cgit v1.2.3-59-g8ed1b