| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <200901271206.51248.rusty@rustcorp.com.au>
Date: Tue, 27 Jan 2009 12:06:50 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: Takashi Iwai <tiwai@...e.de>, Ingo Molnar <mingo@...hat.com>,
Tejun Heo <tj@...nel.org>
Cc: Kyle McMartin <kyle@...radead.org>, linux-kernel@...r.kernel.org,
Eric Dumazet <dada1@...mosbay.com>
Subject: Re: [PATCH] module: kzalloc mod->ref
On Monday 26 January 2009 17:51:21 Rusty Russell wrote:
> On Thursday 15 January 2009 15:21:46 Rusty Russell wrote:
> > In fact, I've decided to go back and add Eric's patch. Since
> > alloc_percpu isn't going to be fixed this merge window, we'll do this
> > now, then simply use alloc_percpu once that is merged.
>
> And with the following fixes, it's in linux-next for tomorrow.
Ingo, can I push this via your tree? I don't expect any problems, but I
hate breaking modules and it'd be nice to have indep testing and get this in
soon; linux-next is off this week.
(The percpu alloc patchset I promised Tejun also depends trivially on this
so getting it upstream will forward that handoff).
Thanks,
Rusty.
Subject: modules: Use a better scheme for refcounting
Date: Thu, 15 May 2008 22:40:37 +0200
From: Eric Dumazet <dada1@...mosbay.com>
(This has become critical with the mainline inclusion of NR_CPUS 4096)
Current refcounting for modules (done if CONFIG_MODULE_UNLOAD=y)
is using a lot of memory.
Each 'struct module' contains an [NR_CPUS] array of full cache lines.
This patch uses existing infrastructure (percpu_modalloc() &
percpu_modfree()) to allocate percpu space for the refcount storage.
Instead of wasting NR_CPUS*128 bytes (on i386), we now use
nr_cpu_ids*sizeof(local_t) bytes.
On a typical distro, where NR_CPUS=8, shiping 2000 modules, we reduce
size of module files by about 2 Mbytes. (1Kb per module)
Instead of having all refcounters in the same memory node - with TLB misses
because of vmalloc() - this new implementation permits to have better
NUMA properties, since each CPU will use storage on its preferred node,
thanks to percpu storage.
Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
include/linux/module.h | 25 ++++++++++++++++---------
kernel/module.c | 35 +++++++++++++++++++++++++----------
2 files changed, 41 insertions(+), 19 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -219,11 +219,6 @@ void *__symbol_get_gpl(const char *symbo
#endif
-struct module_ref
-{
- local_t count;
-} ____cacheline_aligned;
-
enum module_state
{
MODULE_STATE_LIVE,
@@ -344,8 +339,11 @@ struct module
/* Destruction function. */
void (*exit)(void);
- /* Reference counts */
- struct module_ref ref[NR_CPUS];
+#ifdef CONFIG_SMP
+ char *refptr;
+#else
+ local_t ref;
+#endif
#endif
};
#ifndef MODULE_ARCH_INIT
@@ -395,13 +393,22 @@ void __symbol_put(const char *symbol);
#define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
void symbol_put_addr(void *addr);
+static inline local_t *__module_ref_addr(struct module *mod, int cpu)
+{
+#ifdef CONFIG_SMP
+ return (local_t *) (mod->refptr + per_cpu_offset(cpu));
+#else
+ return &mod->ref;
+#endif
+}
+
/* Sometimes we know we already have a refcount, and it's easier not
to handle the error case (which only happens with rmmod --wait). */
static inline void __module_get(struct module *module)
{
if (module) {
BUG_ON(module_refcount(module) == 0);
- local_inc(&module->ref[get_cpu()].count);
+ local_inc(__module_ref_addr(module, get_cpu()));
put_cpu();
}
}
@@ -413,7 +420,7 @@ static inline int try_module_get(struct
if (module) {
unsigned int cpu = get_cpu();
if (likely(module_is_live(module)))
- local_inc(&module->ref[cpu].count);
+ local_inc(__module_ref_addr(module, cpu));
else
ret = 0;
put_cpu();
diff --git a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -573,13 +573,13 @@ static char last_unloaded_module[MODULE_
/* Init the unload section of the module. */
static void module_unload_init(struct module *mod)
{
- unsigned int i;
+ int cpu;
INIT_LIST_HEAD(&mod->modules_which_use_me);
- for (i = 0; i < NR_CPUS; i++)
- local_set(&mod->ref[i].count, 0);
+ for_each_possible_cpu(cpu)
+ local_set(__module_ref_addr(mod, cpu), 0);
/* Hold reference count during initialization. */
- local_set(&mod->ref[raw_smp_processor_id()].count, 1);
+ local_set(__module_ref_addr(mod, raw_smp_processor_id()), 1);
/* Backwards compatibility macros put refcount during init. */
mod->waiter = current;
}
@@ -717,10 +717,11 @@ static int try_stop_module(struct module
unsigned int module_refcount(struct module *mod)
{
- unsigned int i, total = 0;
+ unsigned int total = 0;
+ int cpu;
- for (i = 0; i < NR_CPUS; i++)
- total += local_read(&mod->ref[i].count);
+ for_each_possible_cpu(cpu)
+ total += local_read(__module_ref_addr(mod, cpu));
return total;
}
EXPORT_SYMBOL(module_refcount);
@@ -894,7 +895,7 @@ void module_put(struct module *module)
{
if (module) {
unsigned int cpu = get_cpu();
- local_dec(&module->ref[cpu].count);
+ local_dec(__module_ref_addr(module, cpu));
/* Maybe they're waiting for us to drop reference? */
if (unlikely(!module_is_live(module)))
wake_up_process(module->waiter);
@@ -1464,7 +1465,10 @@ static void free_module(struct module *m
kfree(mod->args);
if (mod->percpu)
percpu_modfree(mod->percpu);
-
+#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP)
+ if (mod->refptr)
+ percpu_modfree(mod->refptr);
+#endif
/* Free lock-classes: */
lockdep_free_key_range(mod->module_core, mod->core_size);
@@ -2011,6 +2015,14 @@ static noinline struct module *load_modu
if (err < 0)
goto free_mod;
+#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP)
+ mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t),
+ mod->name);
+ if (!mod->refptr) {
+ err = -ENOMEM;
+ goto free_mod;
+ }
+#endif
if (pcpuindex) {
/* We have a special allocation for this section. */
percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size,
@@ -2018,7 +2030,7 @@ static noinline struct module *load_modu
mod->name);
if (!percpu) {
err = -ENOMEM;
- goto free_mod;
+ goto free_percpu;
}
sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
mod->percpu = percpu;
@@ -2282,6 +2294,9 @@ static noinline struct module *load_modu
free_percpu:
if (percpu)
percpu_modfree(percpu);
+#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP)
+ percpu_modfree(mod->refptr);
+#endif
free_mod:
kfree(args);
free_hdr:
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists