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Message-ID: <CALCePG2f+aXvabQiJ-=jYL1c4Z-RZW-=Rkj3LLxXDW+WFXwuBA@mail.gmail.com>
Date: Wed, 21 May 2025 14:04:07 -0700
From: Casey Chen <cachen@...estorage.com>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: akpm@...ux-foundation.org, kent.overstreet@...ux.dev, mcgrof@...nel.org,
petr.pavlu@...e.com, samitolvanen@...gle.com, da.gomez@...sung.com,
00107082@....com, linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
linux-mm@...ck.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/1] alloc_tag: handle module codetag load errors as
module load failures
On Wed, May 21, 2025 at 9:06 AM Suren Baghdasaryan <surenb@...gle.com> wrote:
>
> Failures inside codetag_load_module() are currently ignored. As a
> result an error there would not cause a module load failure and freeing
> of the associated resources. Correct this behavior by propagating the
> error code to the caller and handling possible errors. With this change,
> error to allocate percpu counters, which happens at this stage, will not
> be ignored and will cause a module load failure and freeing of resources.
> With this change we also do not need to disable memory allocation
> profiling when this error happens, instead we fail to load the module.
>
> Fixes: 10075262888b ("alloc_tag: allocate percpu counters for module tags dynamically")
> Reported-by: Casey Chen <cachen@...estorage.com>
> Closes: https://lore.kernel.org/all/20250520231620.15259-1-cachen@purestorage.com/
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> Cc: stable@...r.kernel.org
> ---
> include/linux/codetag.h | 8 ++++----
> kernel/module/main.c | 5 +++--
> lib/alloc_tag.c | 12 +++++++-----
> lib/codetag.c | 34 +++++++++++++++++++++++++---------
> 4 files changed, 39 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/codetag.h b/include/linux/codetag.h
> index 0ee4c21c6dbc..5f2b9a1f722c 100644
> --- a/include/linux/codetag.h
> +++ b/include/linux/codetag.h
> @@ -36,8 +36,8 @@ union codetag_ref {
> struct codetag_type_desc {
> const char *section;
> size_t tag_size;
> - void (*module_load)(struct module *mod,
> - struct codetag *start, struct codetag *end);
> + int (*module_load)(struct module *mod,
> + struct codetag *start, struct codetag *end);
> void (*module_unload)(struct module *mod,
> struct codetag *start, struct codetag *end);
> #ifdef CONFIG_MODULES
> @@ -89,7 +89,7 @@ void *codetag_alloc_module_section(struct module *mod, const char *name,
> unsigned long align);
> void codetag_free_module_sections(struct module *mod);
> void codetag_module_replaced(struct module *mod, struct module *new_mod);
> -void codetag_load_module(struct module *mod);
> +int codetag_load_module(struct module *mod);
> void codetag_unload_module(struct module *mod);
>
> #else /* defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES) */
> @@ -103,7 +103,7 @@ codetag_alloc_module_section(struct module *mod, const char *name,
> unsigned long align) { return NULL; }
> static inline void codetag_free_module_sections(struct module *mod) {}
> static inline void codetag_module_replaced(struct module *mod, struct module *new_mod) {}
> -static inline void codetag_load_module(struct module *mod) {}
> +static inline int codetag_load_module(struct module *mod) { return 0; }
> static inline void codetag_unload_module(struct module *mod) {}
>
> #endif /* defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES) */
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 5c6ab20240a6..9861c2ac5fd5 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3399,11 +3399,12 @@ static int load_module(struct load_info *info, const char __user *uargs,
> goto sysfs_cleanup;
> }
>
> + if (codetag_load_module(mod))
> + goto sysfs_cleanup;
> +
> /* Get rid of temporary copy. */
> free_copy(info, flags);
>
> - codetag_load_module(mod);
> -
> /* Done! */
> trace_module_load(mod);
>
> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index 45dae7da70e1..d48b80f3f007 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -607,15 +607,16 @@ static void release_module_tags(struct module *mod, bool used)
> mas_unlock(&mas);
> }
>
> -static void load_module(struct module *mod, struct codetag *start, struct codetag *stop)
> +static int load_module(struct module *mod, struct codetag *start, struct codetag *stop)
> {
> /* Allocate module alloc_tag percpu counters */
> struct alloc_tag *start_tag;
> struct alloc_tag *stop_tag;
> struct alloc_tag *tag;
>
> + /* percpu counters for core allocations are already statically allocated */
> if (!mod)
> - return;
> + return 0;
>
> start_tag = ct_to_alloc_tag(start);
> stop_tag = ct_to_alloc_tag(stop);
> @@ -627,12 +628,13 @@ static void load_module(struct module *mod, struct codetag *start, struct codeta
> free_percpu(tag->counters);
> tag->counters = NULL;
> }
> - shutdown_mem_profiling(true);
> - pr_err("Failed to allocate memory for allocation tag percpu counters in the module %s. Memory allocation profiling is disabled!\n",
> + pr_err("Failed to allocate memory for allocation tag percpu counters in the module %s\n",
> mod->name);
> - break;
> + return -ENOMEM;
> }
> }
> +
> + return 0;
> }
>
> static void replace_module(struct module *mod, struct module *new_mod)
> diff --git a/lib/codetag.c b/lib/codetag.c
> index de332e98d6f5..650d54d7e14d 100644
> --- a/lib/codetag.c
> +++ b/lib/codetag.c
> @@ -167,6 +167,7 @@ static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
> {
> struct codetag_range range;
> struct codetag_module *cmod;
> + int mod_id;
> int err;
>
> range = get_section_range(mod, cttype->desc.section);
> @@ -190,11 +191,20 @@ static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
> cmod->range = range;
>
> down_write(&cttype->mod_lock);
> - err = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL);
> - if (err >= 0) {
> - cttype->count += range_size(cttype, &range);
> - if (cttype->desc.module_load)
> - cttype->desc.module_load(mod, range.start, range.stop);
> + mod_id = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL);
> + if (mod_id >= 0) {
> + if (cttype->desc.module_load) {
> + err = cttype->desc.module_load(mod, range.start, range.stop);
> + if (!err)
> + cttype->count += range_size(cttype, &range);
> + else
> + idr_remove(&cttype->mod_idr, mod_id);
> + } else {
> + cttype->count += range_size(cttype, &range);
> + err = 0;
> + }
> + } else {
> + err = mod_id;
> }
> up_write(&cttype->mod_lock);
>
Overall looks good, just one small nit: should we not increase
cttype->count if there is no module_load callback ?
Personally I prefer having tag allocation and counter allocation at
the same place in move_module() by calling something like
codetag_alloc_module_tag_counter(). But your approach looks more
modular. I don't have a strong preference, you can choose what you
want. Thanks!
int codetag_alloc_module_tag_counter(struct module *mod, void *start_addr,
unsigned long size)
{
struct codetag_type *cttype;
int ret = -ENODEV;
mutex_lock(&codetag_lock);
list_for_each_entry(cttype, &codetag_types, link) {
if (WARN_ON(!cttype->desc.alloc_counter_mem))
break;
down_write(&cttype->mod_lock);
ret = cttype->desc.alloc_counter_mem(mod, start_addr, size);
up_write(&cttype->mod_lock);
break;
}
mutex_unlock(&codetag_lock);
return ret;
}
Casey
> @@ -295,17 +305,23 @@ void codetag_module_replaced(struct module *mod, struct module *new_mod)
> mutex_unlock(&codetag_lock);
> }
>
> -void codetag_load_module(struct module *mod)
> +int codetag_load_module(struct module *mod)
> {
> struct codetag_type *cttype;
> + int ret = 0;
>
> if (!mod)
> - return;
> + return 0;
>
> mutex_lock(&codetag_lock);
> - list_for_each_entry(cttype, &codetag_types, link)
> - codetag_module_init(cttype, mod);
> + list_for_each_entry(cttype, &codetag_types, link) {
> + ret = codetag_module_init(cttype, mod);
> + if (ret)
> + break;
> + }
> mutex_unlock(&codetag_lock);
> +
> + return ret;
> }
>
> void codetag_unload_module(struct module *mod)
>
> base-commit: 9f3e87f6c8d4b28b96eb8bddb22d3ba4b846e10b
> --
> 2.49.0.1112.g889b7c5bd8-goog
>
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