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| author | Breno Leitao <leitao@debian.org> | 2026-07-03 08:22:03 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-07-22 21:12:13 -0700 |
| commit | 7a7d4cdb1be2431dc182c5264cfa916f8df4d4d7 (patch) | |
| tree | 79aa422287961859d267130a5dbf46afa8d53108 /lib | |
| parent | 14a3443133bee17a673b71b7f287c5dca9d7735c (diff) | |
| download | linux-next-7a7d4cdb1be2431dc182c5264cfa916f8df4d4d7.tar.gz linux-next-7a7d4cdb1be2431dc182c5264cfa916f8df4d4d7.zip | |
radix-tree: fix kmemleak false positives on tree head reassignment
Kmemleak periodically reports transient false positives for radix tree
nodes allocated through the IDR, for example:
unreferenced object 0xffff0004d6ac4200 (size 576):
comm "tcpeventd", pid 6412
backtrace (crc 335d668a):
kmem_cache_alloc_noprof
radix_tree_node_alloc
radix_tree_extend
idr_get_free
idr_alloc_cyclic
map_create
__sys_bpf
radix_tree_extend() (grow) and radix_tree_shrink() (shrink) repoint
root->xa_head to a new node. If a kmemleak scan has already walked past
root->xa_head, the new head is not reachable from any scanned pointer
until the following scan, so kmemleak reports it as leaked even though it
is live.
This is the same race fixed for the XArray API in commit a1a029bcea59
("XArray: fix kmemleak false positive in xas_shrink()"). The IDR uses the
radix tree API directly and hits it on both the grow and the shrink path,
so mark the new head as a transient leak in both.
Add a matching kmemleak_transient_leak() stub to the radix tree test
harness so the userspace lib/radix-tree.c build keeps building.
Link: https://lore.kernel.org/20260703-radix-tree-v2-1-38bb6efb5f6e@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/radix-tree.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 976b9bd02a1b..cb5ca920fddb 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -455,6 +455,8 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp, node->slots[0] = (void __rcu *)entry; entry = node_to_entry(node); rcu_assign_pointer(root->xa_head, entry); + /* new head may be missed by an in-progress kmemleak scan */ + kmemleak_transient_leak(node); shift += RADIX_TREE_MAP_SHIFT; } while (shift <= maxshift); out: @@ -495,8 +497,11 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root) if (!node->shift && is_idr(root)) break; - if (radix_tree_is_internal_node(child)) + if (radix_tree_is_internal_node(child)) { entry_to_node(child)->parent = NULL; + /* new head may be missed by an in-progress kmemleak scan */ + kmemleak_transient_leak(entry_to_node(child)); + } /* * We don't need rcu_assign_pointer(), since we are simply |