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DKIM_TRACE(0.00)[suse.cz:+] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: On 10/22/25 19:23, Vlastimil Babka wrote: > Since commit af92793e52c3 ("slab: Introduce kmalloc_nolock() and > kfree_nolock().") there's a possibility in alloc_single_from_new_slab() > that we discard the newly allocated slab if we can't spin and we fail to > trylock. As a result we don't perform inc_slabs_node() later in the > function. Instead we perform a deferred deactivate_slab() which can > either put the unacounted slab on partial list, or discard it > immediately while performing dec_slabs_node(). Either way will cause an > accounting imbalance. > > Fix this and also make the code more robust by performing > inc_slabs_node() in new_slab() itself, and removing it from its callers. > As a side effect, in the theoretical case where the new slab is > immediately leaked due to debugging consistency check failure, it will > be accounted (as full) in /proc/slabinfo anyway, which is not wrong. > > The exceptional caller is early_kmem_cache_node_alloc() where the node > for stats is not yet initialized. We can handle it by using > allocate_slab() there as the gfp flags are known and fixed and we don't > need need new_slab()'s fixups. > > Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().") > Signed-off-by: Vlastimil Babka Pushed to slab/for-next-fixes for testing. Note I haven't seen the imbalance happening. During the ongoing development work I caused a very deterministic underflow elsewhere, decided to make the code more robust by creating this patch, and when going through new_slab() callers I realized it fixes an existing issue.