Commit 842bbaaa7394820c8f1fe0629cd15478653caf86
Committed by
Linus Torvalds
Linus Torvalds
1 parent
561fb765b9
Exists in
master
and in
7 other branches
[PATCH] Module per-cpu alignment cannot always be met
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>
Showing 1 changed file with 11 additions and 4 deletions Side-by-side Diff
kernel/module.c
| ... | ... | @@ -250,13 +250,18 @@ |
| 250 | 250 | /* Created by linker magic */ |
| 251 | 251 | extern char __per_cpu_start[], __per_cpu_end[]; |
| 252 | 252 | |
| 253 | -static void *percpu_modalloc(unsigned long size, unsigned long align) | |
| 253 | +static void *percpu_modalloc(unsigned long size, unsigned long align, | |
| 254 | + const char *name) | |
| 254 | 255 | { |
| 255 | 256 | unsigned long extra; |
| 256 | 257 | unsigned int i; |
| 257 | 258 | void *ptr; |
| 258 | 259 | |
| 259 | - BUG_ON(align > SMP_CACHE_BYTES); | |
| 260 | + if (align > SMP_CACHE_BYTES) { | |
| 261 | + printk(KERN_WARNING "%s: per-cpu alignment %li > %i\n", | |
| 262 | + name, align, SMP_CACHE_BYTES); | |
| 263 | + align = SMP_CACHE_BYTES; | |
| 264 | + } | |
| 260 | 265 | |
| 261 | 266 | ptr = __per_cpu_start; |
| 262 | 267 | for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) { |
| ... | ... | @@ -348,7 +353,8 @@ |
| 348 | 353 | } |
| 349 | 354 | __initcall(percpu_modinit); |
| 350 | 355 | #else /* ... !CONFIG_SMP */ |
| 351 | -static inline void *percpu_modalloc(unsigned long size, unsigned long align) | |
| 356 | +static inline void *percpu_modalloc(unsigned long size, unsigned long align, | |
| 357 | + const char *name) | |
| 352 | 358 | { |
| 353 | 359 | return NULL; |
| 354 | 360 | } |
| ... | ... | @@ -1644,7 +1650,8 @@ |
| 1644 | 1650 | if (pcpuindex) { |
| 1645 | 1651 | /* We have a special allocation for this section. */ |
| 1646 | 1652 | percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size, |
| 1647 | - sechdrs[pcpuindex].sh_addralign); | |
| 1653 | + sechdrs[pcpuindex].sh_addralign, | |
| 1654 | + mod->name); | |
| 1648 | 1655 | if (!percpu) { |
| 1649 | 1656 | err = -ENOMEM; |
| 1650 | 1657 | goto free_mod; |