Commit ac3b43283923 ("module: replace module_layout with module_memory")
reworked the way to handle memory allocations to make it clearer. But it
lost in translation how we handled kmemleak_ignore() or kmemleak_not_leak()
for different ELF sections.
Fix this and clarify the comments a bit more.
Fixes: ac3b43283923 ("module: replace module_layout with module_memory")
Reported-by: Jim Cromie <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>
---
kernel/module/main.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5cc21083af04..d8bb23fa6989 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2233,11 +2233,23 @@ static int move_module(struct module *mod, struct load_info *info)
ptr = module_memory_alloc(mod->mem[type].size, type);
/*
- * The pointer to this block is stored in the module structure
- * which is inside the block. Just mark it as not being a
- * leak.
+ * The pointer to these blocks of memory are stored on the module
+ * structure and we keep that around so long as the module is
+ * around. We only free that memory when we unload the module.
+ * Just mark them as not being a leak then. The .init* ELF
+ * sections *do* get freed after boot so we treat them slightly
+ * differently and only grey them out -- they work as typical
+ * memory allocations which *do* eventually get freed.
*/
- kmemleak_ignore(ptr);
+ switch (type) {
+ case MOD_INIT_TEXT: /* fallthrough */
+ case MOD_INIT_DATA: /* fallthrough */
+ case MOD_INIT_RODATA: /* fallthrough */
+ kmemleak_ignore(ptr);
+ break;
+ default:
+ kmemleak_not_leak(ptr);
+ }
if (!ptr) {
t = type;
goto out_enomem;
--
2.39.2
On Tue, Apr 4, 2023 at 7:27 PM Luis Chamberlain <[email protected]> wrote:
>
> Commit ac3b43283923 ("module: replace module_layout with module_memory")
> reworked the way to handle memory allocations to make it clearer. But it
> lost in translation how we handled kmemleak_ignore() or kmemleak_not_leak()
> for different ELF sections.
>
> Fix this and clarify the comments a bit more.
>
> Fixes: ac3b43283923 ("module: replace module_layout with module_memory")
> Reported-by: Jim Cromie <[email protected]>
> Signed-off-by: Luis Chamberlain <[email protected]>
Acked-by: Song Liu <[email protected]>
Thanks for the fix!
> ---
> kernel/module/main.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 5cc21083af04..d8bb23fa6989 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2233,11 +2233,23 @@ static int move_module(struct module *mod, struct load_info *info)
> ptr = module_memory_alloc(mod->mem[type].size, type);
>
> /*
> - * The pointer to this block is stored in the module structure
> - * which is inside the block. Just mark it as not being a
> - * leak.
> + * The pointer to these blocks of memory are stored on the module
> + * structure and we keep that around so long as the module is
> + * around. We only free that memory when we unload the module.
> + * Just mark them as not being a leak then. The .init* ELF
> + * sections *do* get freed after boot so we treat them slightly
> + * differently and only grey them out -- they work as typical
> + * memory allocations which *do* eventually get freed.
> */
> - kmemleak_ignore(ptr);
> + switch (type) {
> + case MOD_INIT_TEXT: /* fallthrough */
> + case MOD_INIT_DATA: /* fallthrough */
> + case MOD_INIT_RODATA: /* fallthrough */
> + kmemleak_ignore(ptr);
> + break;
> + default:
> + kmemleak_not_leak(ptr);
> + }
> if (!ptr) {
> t = type;
> goto out_enomem;
> --
> 2.39.2
>
On Tue, Apr 04, 2023 at 07:26:57PM -0700, Luis Chamberlain wrote:
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 5cc21083af04..d8bb23fa6989 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2233,11 +2233,23 @@ static int move_module(struct module *mod, struct load_info *info)
> ptr = module_memory_alloc(mod->mem[type].size, type);
>
> /*
> - * The pointer to this block is stored in the module structure
> - * which is inside the block. Just mark it as not being a
> - * leak.
> + * The pointer to these blocks of memory are stored on the module
> + * structure and we keep that around so long as the module is
> + * around. We only free that memory when we unload the module.
> + * Just mark them as not being a leak then. The .init* ELF
> + * sections *do* get freed after boot so we treat them slightly
> + * differently and only grey them out -- they work as typical
> + * memory allocations which *do* eventually get freed.
> */
> - kmemleak_ignore(ptr);
> + switch (type) {
> + case MOD_INIT_TEXT: /* fallthrough */
> + case MOD_INIT_DATA: /* fallthrough */
> + case MOD_INIT_RODATA: /* fallthrough */
> + kmemleak_ignore(ptr);
> + break;
> + default:
> + kmemleak_not_leak(ptr);
> + }
This works as well but if you want to keep it simple, just call
kmemleak_not_leak() in all cases. When freeing the init sections, they
would be removed from the kmemleak tracing anyway.
--
Catalin
On Tue, Apr 11, 2023 at 04:17:35PM +0100, Catalin Marinas wrote:
> On Tue, Apr 04, 2023 at 07:26:57PM -0700, Luis Chamberlain wrote:
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index 5cc21083af04..d8bb23fa6989 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -2233,11 +2233,23 @@ static int move_module(struct module *mod, struct load_info *info)
> > ptr = module_memory_alloc(mod->mem[type].size, type);
> >
> > /*
> > - * The pointer to this block is stored in the module structure
> > - * which is inside the block. Just mark it as not being a
> > - * leak.
> > + * The pointer to these blocks of memory are stored on the module
> > + * structure and we keep that around so long as the module is
> > + * around. We only free that memory when we unload the module.
> > + * Just mark them as not being a leak then. The .init* ELF
> > + * sections *do* get freed after boot so we treat them slightly
> > + * differently and only grey them out -- they work as typical
> > + * memory allocations which *do* eventually get freed.
> > */
> > - kmemleak_ignore(ptr);
> > + switch (type) {
> > + case MOD_INIT_TEXT: /* fallthrough */
> > + case MOD_INIT_DATA: /* fallthrough */
> > + case MOD_INIT_RODATA: /* fallthrough */
> > + kmemleak_ignore(ptr);
> > + break;
> > + default:
> > + kmemleak_not_leak(ptr);
> > + }
>
> This works as well but if you want to keep it simple, just call
> kmemleak_not_leak() in all cases. When freeing the init sections, they
> would be removed from the kmemleak tracing anyway.
It is up to you as you were the one who originally used different calls
here, so I didn't want to change the old mechanism. Changing it to use
kmemleak_not_leak() would be a functional change, do we loose anything
for using kmemleak_not_leak() for all? Ie, why had you used a different
set of calls when you first added this depending on the if its init or
not? Is the value no longer there?
Luis