| Message ID | 20230405022702.753323-2-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | module: avoid userspace pressure on unwanted allocations | expand |
On Tue, Apr 4, 2023 at 7:27 PM Luis Chamberlain <mcgrof@kernel.org> 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 <jim.cromie@gmail.com> > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Song Liu <song@kernel.org> 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.
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
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;
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 <jim.cromie@gmail.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- kernel/module/main.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)