Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] The patch addresses a compile-time BUILD_BUG_ON failure that no longer exists, referencing a deleted structure (`struct kmem_cache_cpu`) and function (`alloc_kmem_cache_cpus()`). Both have been removed from the upstream kernel. The only remaining BUILD_BUG_ON checking `PERCPU_DYNAMIC_EARLY_SIZE` in SLUB is in `alloc_kmem_cache_stats()`, which evaluates `sizeof(struct kmem_cache_stats)`. Because `struct kmem_cache_stats` consists solely of an integer array, its size is entirely unaffected by `CONFIG_DEPT` or `local_lock_t`. Thus, this patch needlessly increases the dynamically reserved per-CPU memory based on an obsolete and misleading justification. --
commit 279fb8fb2919a407c18ab625ec67d2a3430b7b4d Author: Byungchul Park <[email protected]> mm: percpu: increase PERCPU_DYNAMIC_SIZE_SHIFT on DEPT and large PAGE_SIZE This commit increases PERCPU_DYNAMIC_SIZE_SHIFT to 11 when both CONFIG_DEPT and a PAGE_SIZE larger than 4KiB are enabled. It aims to prevent a build failure related to the size of struct kmem_cache_cpu. > Yunseong reported a build failure due to the BUILD_BUG_ON() statement in > alloc_kmem_cache_cpus(). In the following test: > > PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * > sizeof(struct kmem_cache_cpu) [Severity: Medium] Are we referencing structures and functions that have been removed from the upstream kernel? Both alloc_kmem_cache_cpus() and struct kmem_cache_cpu no longer exist upstream. The only remaining BUILD_BUG_ON() checking PERCPU_DYNAMIC_EARLY_SIZE in SLUB is in alloc_kmem_cache_stats(): mm/slub.c:alloc_kmem_cache_stats() { BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_stats)); } Since struct kmem_cache_stats consists solely of an integer array, its size is entirely unaffected by CONFIG_DEPT or local_lock_t. Does this mean the increase in dynamically reserved per-CPU memory is no longer needed? > diff --git a/include/linux/percpu.h b/include/linux/percpu.h > index 85bf8dd9f0874..dd74321d4bbd0 100644 > --- a/include/linux/percpu.h > +++ b/include/linux/percpu.h > @@ -43,7 +43,11 @@ > # define PERCPU_DYNAMIC_SIZE_SHIFT 12 > #endif /* LOCKDEP and PAGE_SIZE > 4KiB */ > #else > +#if defined(CONFIG_DEPT) && !defined(CONFIG_PAGE_SIZE_4KB) > +#define PERCPU_DYNAMIC_SIZE_SHIFT 11 > +#else > #define PERCPU_DYNAMIC_SIZE_SHIFT 10 > +#endif /* DEPT and PAGE_SIZE > 4KiB */ > #endif -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=38
