From b29acbdcf877009af3f1fc0750bcac314c51e055 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Mon, 1 Dec 2008 13:13:47 -0800 Subject: mm: vmalloc fix lazy unmapping cache aliasing Jim Radford has reported that the vmap subsystem rewrite was sometimes causing his VIVT ARM system to behave strangely (seemed like going into infinite loops trying to fault in pages to userspace). We determined that the problem was most likely due to a cache aliasing issue. flush_cache_vunmap was only being called at the moment the page tables were to be taken down, however with lazy unmapping, this can happen after the page has subsequently been freed and allocated for something else. The dangling alias may still have dirty data attached to it. The fix for this problem is to do the cache flushing when the caller has called vunmap -- it would be a bug for them to write anything else to the mapping at that point. That appeared to solve Jim's problems. Reported-by: Jim Radford Signed-off-by: Nick Piggin Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 30f826d484f0..f3f6e0758562 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -77,7 +77,6 @@ static void vunmap_page_range(unsigned long addr, unsigned long end) BUG_ON(addr >= end); pgd = pgd_offset_k(addr); - flush_cache_vunmap(addr, end); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) @@ -543,9 +542,10 @@ static void purge_vmap_area_lazy(void) } /* - * Free and unmap a vmap area + * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been + * called for the correct range previously. */ -static void free_unmap_vmap_area(struct vmap_area *va) +static void free_unmap_vmap_area_noflush(struct vmap_area *va) { va->flags |= VM_LAZY_FREE; atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr); @@ -553,6 +553,15 @@ static void free_unmap_vmap_area(struct vmap_area *va) try_purge_vmap_area_lazy(); } +/* + * Free and unmap a vmap area + */ +static void free_unmap_vmap_area(struct vmap_area *va) +{ + flush_cache_vunmap(va->va_start, va->va_end); + free_unmap_vmap_area_noflush(va); +} + static struct vmap_area *find_vmap_area(unsigned long addr) { struct vmap_area *va; @@ -734,7 +743,7 @@ static void free_vmap_block(struct vmap_block *vb) spin_unlock(&vmap_block_tree_lock); BUG_ON(tmp != vb); - free_unmap_vmap_area(vb->va); + free_unmap_vmap_area_noflush(vb->va); call_rcu(&vb->rcu_head, rcu_free_vb); } @@ -796,6 +805,9 @@ static void vb_free(const void *addr, unsigned long size) BUG_ON(size & ~PAGE_MASK); BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC); + + flush_cache_vunmap((unsigned long)addr, (unsigned long)addr + size); + order = get_order(size); offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1); -- cgit v1.2.3-58-ga151 From 9c24624727f6d6c460e45762a408ca5f5b9b8ef2 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Tue, 9 Dec 2008 13:14:27 -0800 Subject: KSYM_SYMBOL_LEN fixes Miles Lane tailing /sys files hit a BUG which Pekka Enberg has tracked to my 966c8c12dc9e77f931e2281ba25d2f0244b06949 sprint_symbol(): use less stack exposing a bug in slub's list_locations() - kallsyms_lookup() writes a 0 to namebuf[KSYM_NAME_LEN-1], but that was beyond the end of page provided. The 100 slop which list_locations() allows at end of page looks roughly enough for all the other stuff it might print after the symbol before it checks again: break out KSYM_SYMBOL_LEN earlier than before. Latencytop and ftrace and are using KSYM_NAME_LEN buffers where they need KSYM_SYMBOL_LEN buffers, and vmallocinfo a 2*KSYM_NAME_LEN buffer where it wants a KSYM_SYMBOL_LEN buffer: fix those before anyone copies them. [akpm@linux-foundation.org: ftrace.h needs module.h] Signed-off-by: Hugh Dickins Cc: Christoph Lameter Cc Miles Lane Acked-by: Pekka Enberg Acked-by: Steven Rostedt Acked-by: Frederic Weisbecker Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/base.c | 2 +- include/linux/ftrace.h | 3 ++- kernel/latencytop.c | 2 +- mm/slub.c | 2 +- mm/vmalloc.c | 2 +- 5 files changed, 6 insertions(+), 5 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/fs/proc/base.c b/fs/proc/base.c index 486cf3fe7139..d4677603c889 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -371,7 +371,7 @@ static int lstats_show_proc(struct seq_file *m, void *v) task->latency_record[i].time, task->latency_record[i].max); for (q = 0; q < LT_BACKTRACEDEPTH; q++) { - char sym[KSYM_NAME_LEN]; + char sym[KSYM_SYMBOL_LEN]; char *c; if (!task->latency_record[i].backtrace[q]) break; diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 703eb53cfa2b..9c5bc6be2b09 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -6,6 +6,7 @@ #include #include #include +#include #include #ifdef CONFIG_FUNCTION_TRACER @@ -231,7 +232,7 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { } struct boot_trace { pid_t caller; - char func[KSYM_NAME_LEN]; + char func[KSYM_SYMBOL_LEN]; int result; unsigned long long duration; /* usecs */ ktime_t calltime; diff --git a/kernel/latencytop.c b/kernel/latencytop.c index 5e7b45c56923..449db466bdbc 100644 --- a/kernel/latencytop.c +++ b/kernel/latencytop.c @@ -191,7 +191,7 @@ static int lstats_show(struct seq_file *m, void *v) latency_record[i].time, latency_record[i].max); for (q = 0; q < LT_BACKTRACEDEPTH; q++) { - char sym[KSYM_NAME_LEN]; + char sym[KSYM_SYMBOL_LEN]; char *c; if (!latency_record[i].backtrace[q]) break; diff --git a/mm/slub.c b/mm/slub.c index 749588a50a5a..a2cd47d89e0a 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3597,7 +3597,7 @@ static int list_locations(struct kmem_cache *s, char *buf, for (i = 0; i < t.count; i++) { struct location *l = &t.loc[i]; - if (len > PAGE_SIZE - 100) + if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100) break; len += sprintf(buf + len, "%7ld ", l->count); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index f3f6e0758562..1ddb77ba3995 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1717,7 +1717,7 @@ static int s_show(struct seq_file *m, void *p) v->addr, v->addr + v->size, v->size); if (v->caller) { - char buff[2 * KSYM_NAME_LEN]; + char buff[KSYM_SYMBOL_LEN]; seq_putc(m, ' '); sprint_symbol(buff, (unsigned long)v->caller); -- cgit v1.2.3-58-ga151