On 9/5/24 20:48, Shakeel Butt wrote: >> > --- >> > v3: https://lore.kernel.org/all/20240829175339.2424521-1-shakeel.butt@xxxxxxxxx/ >> > Changes since v3: >> > - Add kernel doc for kmem_cache_charge. >> > >> > v2: https://lore.kernel.org/all/20240827235228.1591842-1-shakeel.butt@xxxxxxxxx/ >> > Change since v2: >> > - Add handling of already charged large kmalloc objects. >> > - Move the normal kmalloc cache check into a function. >> > >> > v1: https://lore.kernel.org/all/20240826232908.4076417-1-shakeel.butt@xxxxxxxxx/ >> > Changes since v1: >> > - Correctly handle large allocations which bypass slab >> > - Rearrange code to avoid compilation errors for !CONFIG_MEMCG builds >> > >> > RFC: https://lore.kernel.org/all/20240824010139.1293051-1-shakeel.butt@xxxxxxxxx/ >> > Changes since the RFC: >> > - Added check for already charged slab objects. >> > - Added performance results from neper's tcp_crr >> > >> > >> > include/linux/slab.h | 20 ++++++++++++++ >> > mm/slab.h | 7 +++++ >> > mm/slub.c | 49 +++++++++++++++++++++++++++++++++ >> > net/ipv4/inet_connection_sock.c | 5 ++-- >> > 4 files changed, 79 insertions(+), 2 deletions(-) >> > >> > diff --git a/include/linux/slab.h b/include/linux/slab.h >> > index eb2bf4629157..68789c79a530 100644 >> > --- a/include/linux/slab.h >> > +++ b/include/linux/slab.h >> > @@ -547,6 +547,26 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, >> > gfp_t gfpflags) __assume_slab_alignment __malloc; >> > #define kmem_cache_alloc_lru(...) alloc_hooks(kmem_cache_alloc_lru_noprof(__VA_ARGS__)) >> > >> > +/** >> > + * kmem_cache_charge - memcg charge an already allocated slab memory >> > + * @objp: address of the slab object to memcg charge. >> > + * @gfpflags: describe the allocation context >> > + * >> > + * kmem_cache_charge is the normal method to charge a slab object to the current what is "normal method"? >> > + * memcg. The objp should be pointer returned by the slab allocator functions >> > + * like kmalloc or kmem_cache_alloc. The memcg charge behavior can be controller >> >> s/controller/controlled > > Thanks. Vlastimil please fix this when you pick this up. I felt it could be improved more, so ended up with this. Thoughts? /** * kmem_cache_charge - memcg charge an already allocated slab memory * @objp: address of the slab object to memcg charge * @gfpflags: describe the allocation context * * kmem_cache_charge allows charging a slab object to the current memcg, * primarily in cases where charging at allocation time might not be possible * because the target memcg is not known (i.e. softirq context) * * The objp should be pointer returned by the slab allocator functions like * kmalloc (with __GFP_ACCOUNT in flags) or kmem_cache_alloc. The memcg charge * behavior can be controlled through gfpflags parameter, which affects how the * necessary internal metadata can be allocated. Including __GFP_NOFAIL denotes * that overcharging is requested instead of failure, but is not applied for the * internal metadata allocation. * * There are several cases where it will return true even if the charging was * not done: * More specifically: * * 1. For !CONFIG_MEMCG or cgroup_disable=memory systems. * 2. Already charged slab objects. * 3. For slab objects from KMALLOC_NORMAL caches - allocated by kmalloc() * without __GFP_ACCOUNT * 4. Allocating internal metadata has failed * * Return: true if charge was successful otherwise false. */ >> > + >> > + /* Ignore KMALLOC_NORMAL cache to avoid circular dependency. */ >> >> Is it possible to point to the commit that has the explanation here? >> The one you pointed me to before? Otherwise it's not really obvious >> where the circular dependency comes from (at least to me). >> > > Not sure about the commit reference. We can add more text here. > Vlastimil, how much detail do you prefer? What about: /* * Ignore KMALLOC_NORMAL cache to avoid possible circular dependency * of slab_obj_exts being allocated from the same slab and thus the slab * becoming effectively unfreeable. */ > thanks, > Shakeel
