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authorRusty Russell <rusty@rustcorp.com.au>2005-08-10 13:52:38 +0100
committerChris Wright <chrisw@osdl.org>2005-08-14 17:20:11 -0700
commit24eda4e69d4f0a4d5a66c8b5a8fa9b895d832368 (patch)
treed0396ba53a81783db3ba6ae6f29349504cf66809
parenta3692f99ef19cfb7fe0420837852108450dd8124 (diff)
[PATCH] Module per-cpu alignment cannot always be met
Fwd from Daniel Drake <dsd@gentoo.org>. The module code assumes noone will ever ask for a per-cpu area more than SMP_CACHE_BYTES aligned. However, as these cases show, gcc asks sometimes asks for 32-byte alignment for the per-cpu section on a module, and if CONFIG_X86_L1_CACHE_SHIFT is 4, we hit that BUG_ON(). This is obviously an unusual combination, as there have been few reports, but better to warn than die. See: http://www.ussg.iu.edu/hypermail/linux/kernel/0409.0/0768.html And more recently: http://bugs.gentoo.org/show_bug.cgi?id=97006 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Chris Wright <chrisw@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--kernel/module.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 83b3d376708c..71ff04191d47 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -249,13 +249,18 @@ static inline unsigned int block_size(int val)
/* Created by linker magic */
extern char __per_cpu_start[], __per_cpu_end[];
-static void *percpu_modalloc(unsigned long size, unsigned long align)
+static void *percpu_modalloc(unsigned long size, unsigned long align,
+ const char *name)
{
unsigned long extra;
unsigned int i;
void *ptr;
- BUG_ON(align > SMP_CACHE_BYTES);
+ if (align > SMP_CACHE_BYTES) {
+ printk(KERN_WARNING "%s: per-cpu alignment %li > %i\n",
+ name, align, SMP_CACHE_BYTES);
+ align = SMP_CACHE_BYTES;
+ }
ptr = __per_cpu_start;
for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
@@ -347,7 +352,8 @@ static int percpu_modinit(void)
}
__initcall(percpu_modinit);
#else /* ... !CONFIG_SMP */
-static inline void *percpu_modalloc(unsigned long size, unsigned long align)
+static inline void *percpu_modalloc(unsigned long size, unsigned long align,
+ const char *name)
{
return NULL;
}
@@ -1554,7 +1560,8 @@ static struct module *load_module(void __user *umod,
if (pcpuindex) {
/* We have a special allocation for this section. */
percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size,
- sechdrs[pcpuindex].sh_addralign);
+ sechdrs[pcpuindex].sh_addralign,
+ mod->name);
if (!percpu) {
err = -ENOMEM;
goto free_mod;