Commit 09c46563 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Andrew Morton
Browse files

codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations 

If slabobj_ext vector allocation for a slab object fails and later on it
succeeds for another object in the same slab, the slabobj_ext for the
original object will be NULL and will be flagged in case when
CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled.

Mark failed slabobj_ext vector allocations using a new objext_flags flag
stored in the lower bits of slab->obj_exts.  When new allocation succeeds
it marks all tag references in the same slabobj_ext vector as empty to
avoid warnings implemented by CONFIG_MEM_ALLOC_PROFILING_DEBUG checks.

Link: https://lkml.kernel.org/r/20240321163705.3067592-36-surenb@google.com


Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Tested-by: default avatarKees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d224eb02

include/linux/memcontrol.h

+3 −1
Original line number Diff line number Diff line
@@ -366,8 +366,10 @@ enum page_memcg_data_flags { 
#endif /* CONFIG_MEMCG */



enum objext_flags {

	/* slabobj_ext vector failed to allocate */

	OBJEXTS_ALLOC_FAIL = __FIRST_OBJEXT_FLAG,

	/* the next bit after the last actual flag */

	__NR_OBJEXTS_FLAGS  = __FIRST_OBJEXT_FLAG,

	__NR_OBJEXTS_FLAGS  = (__FIRST_OBJEXT_FLAG << 1),

};



#define OBJEXTS_FLAGS_MASK (__NR_OBJEXTS_FLAGS - 1)

mm/slub.c

+39 −7
Original line number Diff line number Diff line
@@ -1891,9 +1891,33 @@ static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) 
	}

}



static inline void mark_failed_objexts_alloc(struct slab *slab)

{

	slab->obj_exts = OBJEXTS_ALLOC_FAIL;

}



static inline void handle_failed_objexts_alloc(unsigned long obj_exts,

			struct slabobj_ext *vec, unsigned int objects)

{

	/*

	 * If vector previously failed to allocate then we have live

	 * objects with no tag reference. Mark all references in this

	 * vector as empty to avoid warnings later on.

	 */

	if (obj_exts & OBJEXTS_ALLOC_FAIL) {

		unsigned int i;



		for (i = 0; i < objects; i++)

			set_codetag_empty(&vec[i].ref);

	}

}



#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */



static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}

static inline void mark_failed_objexts_alloc(struct slab *slab) {}

static inline void handle_failed_objexts_alloc(unsigned long obj_exts,

			struct slabobj_ext *vec, unsigned int objects) {}



#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
@@ -1909,29 +1933,37 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, 
			       gfp_t gfp, bool new_slab)

{

	unsigned int objects = objs_per_slab(s, slab);

	unsigned long obj_exts;

	void *vec;

	unsigned long new_exts;

	unsigned long old_exts;

	struct slabobj_ext *vec;



	gfp &= ~OBJCGS_CLEAR_MASK;

	/* Prevent recursive extension vector allocation */

	gfp |= __GFP_NO_OBJ_EXT;

	vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp,

			   slab_nid(slab));

	if (!vec)

	if (!vec) {

		/* Mark vectors which failed to allocate */

		if (new_slab)

			mark_failed_objexts_alloc(slab);



		return -ENOMEM;

	}



	obj_exts = (unsigned long)vec;

	new_exts = (unsigned long)vec;

#ifdef CONFIG_MEMCG

	obj_exts |= MEMCG_DATA_OBJEXTS;

	new_exts |= MEMCG_DATA_OBJEXTS;

#endif

	old_exts = slab->obj_exts;

	handle_failed_objexts_alloc(old_exts, vec, objects);

	if (new_slab) {

		/*

		 * If the slab is brand new and nobody can yet access its

		 * obj_exts, no synchronization is required and obj_exts can

		 * be simply assigned.

		 */

		slab->obj_exts = obj_exts;

	} else if (cmpxchg(&slab->obj_exts, 0, obj_exts)) {

		slab->obj_exts = new_exts;

	} else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) {

		/*

		 * If the slab is already in use, somebody can allocate and

		 * assign slabobj_exts in parallel. In this case the existing