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codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations

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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: Suren Baghdasaryan <surenb@google.com>
Tested-by: Kees 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Suren Baghdasaryan 2024-03-21 09:36:57 -07:00 committed by Andrew Morton
parent d224eb0287
commit 09c46563ff
2 changed files with 43 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
include/linux/memcontrol.h
View file

@ -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)

48
mm/slub.c
View file

@ -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)
return -ENOMEM;
if (!vec) {
/* Mark vectors which failed to allocate */
if (new_slab)
mark_failed_objexts_alloc(slab);
obj_exts = (unsigned long)vec;
return -ENOMEM;
}
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