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SubjectRe: [PATCH 1/2] kmemleak: Inform kmemleak about kernel stack allocation
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On Sat, 2009-08-29 at 15:28 +0100, Catalin Marinas wrote:
> On Sat, 2009-08-29 at 15:29 +0200, Ingo Molnar wrote:
> > * Catalin Marinas <catalin.marinas@arm.com> wrote:
> >
> > > Traversing all the tasks in the system for scanning the kernel
> > > stacks requires locking which increases the kernel latency
> > > considerably. This patch informs kmemleak about newly allocated or
> > > freed stacks so that they are treated as any other allocated
> > > object. Subsequent patch will remove the explicit stack scanning
> > > from mm/kmemleak.c.
> > >
> > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Ingo Molnar <mingo@redhat.com>
> > > ---
> > > arch/x86/include/asm/thread_info.h | 7 ++++++-
> > > arch/x86/kernel/process.c | 2 ++
> > > kernel/fork.c | 7 ++++++-
> > > 3 files changed, 14 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> > > index fad7d40..f26432a 100644
> > > --- a/arch/x86/include/asm/thread_info.h
> > > +++ b/arch/x86/include/asm/thread_info.h
> > > @@ -162,7 +162,12 @@ struct thread_info {
> > > #define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
> > >
> > > #define alloc_thread_info(tsk) \
> > > - ((struct thread_info *)__get_free_pages(THREAD_FLAGS, THREAD_ORDER))
> > > +({ \
> > > + struct thread_info *ti = (struct thread_info *) \
> > > + __get_free_pages(THREAD_FLAGS, THREAD_ORDER); \
> > > + kmemleak_alloc(ti, THREAD_SIZE, 1, THREAD_FLAGS); \
> > > + ti; \
> > > +})
> >
> > Sidenote:this used to be a trivial wrapper to gfp so it was
> > borderline OK as a CPP macro - now it's a non-trivial CPP wrapper
> > macro which is not OK. Mind converting it to an inline function?
>
> I tried this first but got compilation errors in files that didn't even
> call this function. To make it workable, thread_info.h would need to
> include additional headers. If that's acceptable, I can post an updated
> patch.

Actually I think it's only the kmemleak.h header but it would get
included via thread_info.h in many other files. An alternative is to
make kmemleak_alloc() etc. return the pointer passed as argument and
keep the macro something like:

kmemleak_alloc(__get_free_pages(...), ...)

though it is still a bit long.

--
Catalin



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