From 7c692cbade8b8884f1c20500393bcc7cd6d24ef8 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Wed, 21 May 2008 22:53:13 +0200 Subject: tasklets: new tasklet scheduling function Rationale: kmemcheck needs to be able to schedule a tasklet without touching any dynamically allocated memory _at_ _all_ (since that would lead to a recursive page fault). This tasklet is used for writing the error reports to the kernel log. The new scheduling function avoids touching any other tasklets by inserting the new tasklist as the head of the "tasklet_hi" list instead of on the tail. Also don't wake up the softirq thread lest the scheduler access some tracked memory and we go down with a recursive page fault. In this case, we'd better just wait for the maximum time of 1/HZ for the message to appear. Signed-off-by: Vegard Nossum --- kernel/softirq.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'kernel') diff --git a/kernel/softirq.c b/kernel/softirq.c index 258885a543db..b41fb710e114 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -382,6 +382,17 @@ void __tasklet_hi_schedule(struct tasklet_struct *t) EXPORT_SYMBOL(__tasklet_hi_schedule); +void __tasklet_hi_schedule_first(struct tasklet_struct *t) +{ + BUG_ON(!irqs_disabled()); + + t->next = __get_cpu_var(tasklet_hi_vec).head; + __get_cpu_var(tasklet_hi_vec).head = t; + __raise_softirq_irqoff(HI_SOFTIRQ); +} + +EXPORT_SYMBOL(__tasklet_hi_schedule_first); + static void tasklet_action(struct softirq_action *a) { struct tasklet_struct *list; -- cgit v1.2.3 From dfec072ecd35ba6ecad2d51dde325253ac9a2936 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Fri, 4 Apr 2008 00:51:41 +0200 Subject: kmemcheck: add the kmemcheck core General description: kmemcheck is a patch to the linux kernel that detects use of uninitialized memory. It does this by trapping every read and write to memory that was allocated dynamically (e.g. using kmalloc()). If a memory address is read that has not previously been written to, a message is printed to the kernel log. Thanks to Andi Kleen for the set_memory_4k() solution. Andrew Morton suggested documenting the shadow member of struct page. Signed-off-by: Vegard Nossum Signed-off-by: Pekka Enberg [export kmemcheck_mark_initialized] [build fix for setup_max_cpus] Signed-off-by: Ingo Molnar [rebased for mainline inclusion] Signed-off-by: Vegard Nossum --- kernel/sysctl.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index ce664f98e3fb..9ef80bba3509 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -959,6 +960,17 @@ static struct ctl_table kern_table[] = { .proc_handler = &proc_dointvec, }, #endif +#ifdef CONFIG_KMEMCHECK + { + .ctl_name = CTL_UNNUMBERED, + .procname = "kmemcheck", + .data = &kmemcheck_enabled, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, +#endif + /* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt -- cgit v1.2.3 From 2dff440525f8faba8836e9f05297b76f23b4af30 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sat, 31 May 2008 15:56:17 +0200 Subject: kmemcheck: add mm functions With kmemcheck enabled, the slab allocator needs to do this: 1. Tell kmemcheck to allocate the shadow memory which stores the status of each byte in the allocation proper, e.g. whether it is initialized or uninitialized. 2. Tell kmemcheck which parts of memory that should be marked uninitialized. There are actually a few more states, such as "not yet allocated" and "recently freed". If a slab cache is set up using the SLAB_NOTRACK flag, it will never return memory that can take page faults because of kmemcheck. If a slab cache is NOT set up using the SLAB_NOTRACK flag, callers can still request memory with the __GFP_NOTRACK flag. This does not prevent the page faults from occuring, however, but marks the object in question as being initialized so that no warnings will ever be produced for this object. In addition to (and in contrast to) __GFP_NOTRACK, the __GFP_NOTRACK_FALSE_POSITIVE flag indicates that the allocation should not be tracked _because_ it would produce a false positive. Their values are identical, but need not be so in the future (for example, we could now enable/disable false positives with a config option). Parts of this patch were contributed by Pekka Enberg but merged for atomicity. Signed-off-by: Vegard Nossum Signed-off-by: Pekka Enberg Signed-off-by: Ingo Molnar [rebased for mainline inclusion] Signed-off-by: Vegard Nossum --- kernel/fork.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 4430eb1376f2..be022c200da6 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -178,7 +178,7 @@ void __init fork_init(unsigned long mempages) /* create a slab on which task_structs can be allocated */ task_struct_cachep = kmem_cache_create("task_struct", sizeof(struct task_struct), - ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL); + ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); #endif /* do the arch specific task caches init */ @@ -1470,20 +1470,20 @@ void __init proc_caches_init(void) { sighand_cachep = kmem_cache_create("sighand_cache", sizeof(struct sighand_struct), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, - sighand_ctor); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| + SLAB_NOTRACK, sighand_ctor); signal_cachep = kmem_cache_create("signal_cache", sizeof(struct signal_struct), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); files_cachep = kmem_cache_create("files_cache", sizeof(struct files_struct), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); fs_cachep = kmem_cache_create("fs_cache", sizeof(struct fs_struct), 0, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); mm_cachep = kmem_cache_create("mm_struct", sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, - SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); mmap_init(); } -- cgit v1.2.3 From 1744a21d57d9c60136461adb6afa85e51b3e94d9 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sat, 28 Feb 2009 08:29:44 +0100 Subject: trace: annotate bitfields in struct ring_buffer_event This gets rid of a heap of false-positive warnings from the tracer code due to the use of bitfields. [rebased for mainline inclusion] Signed-off-by: Vegard Nossum --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2e642b2b7253..dc4dc70171ce 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -1270,6 +1271,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, if (tail < BUF_PAGE_SIZE) { /* Mark the rest of the page with padding */ event = __rb_page_index(tail_page, tail); + kmemcheck_annotate_bitfield(event, bitfield); rb_event_set_padding(event); } @@ -1327,6 +1329,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return NULL; event = __rb_page_index(tail_page, tail); + kmemcheck_annotate_bitfield(event, bitfield); rb_update_event(event, type, length); /* The passed in type is zero for DATA */ -- cgit v1.2.3 From 7a0aeb14e18ad59394bd9bbc6e57fb345819e748 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sat, 16 May 2009 11:28:33 +0200 Subject: signal: fix __send_signal() false positive kmemcheck warning This false positive is due to field padding in struct sigqueue. When this dynamically allocated structure is copied to the stack (in arch- specific delivery code), kmemcheck sees a read from the padding, which is, naturally, uninitialized. Hide the false positive using the __GFP_NOTRACK_FALSE_POSITIVE flag. Also made the rlimit override code a bit clearer by introducing a new variable. Cc: Oleg Nesterov Signed-off-by: Vegard Nossum --- kernel/signal.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index 809a228019ad..d81f4952eebb 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -832,6 +832,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, { struct sigpending *pending; struct sigqueue *q; + int override_rlimit; trace_sched_signal_send(sig, t); @@ -863,9 +864,13 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, make sure at least one signal gets delivered and don't pass on the info struct. */ - q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN && - (is_si_special(info) || - info->si_code >= 0))); + if (sig < SIGRTMIN) + override_rlimit = (is_si_special(info) || info->si_code >= 0); + else + override_rlimit = 0; + + q = __sigqueue_alloc(t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE, + override_rlimit); if (q) { list_add_tail(&q->list, &pending->list); switch ((unsigned long) info) { -- cgit v1.2.3