On Fri, 14 Nov 2025 08:43:46 -0500 Steven Rostedt <[email protected]> wrote:
> I need to add a comment here that entries is not bound by nr_entries. > > https://lore.kernel.org/all/[email protected]/ > > Maybe this?: Or better yet, if this compiles (I haven't tried): diff --git a/include/linux/unwind_deferred_types.h b/include/linux/unwind_deferred_types.h index 33b62ac25c86..253a69b21e76 100644 --- a/include/linux/unwind_deferred_types.h +++ b/include/linux/unwind_deferred_types.h @@ -2,10 +2,14 @@ #ifndef _LINUX_UNWIND_USER_DEFERRED_TYPES_H #define _LINUX_UNWIND_USER_DEFERRED_TYPES_H +/* Make the cache fit in a 4K page */ +#define UNWIND_MAX_ENTRIES \ + ((SZ_4K - offset_of(struct unwind_cache, entries)) / sizeof(long)) + struct unwind_cache { unsigned long unwind_completed; unsigned int nr_entries; - unsigned long entries[]; + unsigned long entries[UNWIND_MAX_ENTRIES]; }; /* diff --git a/kernel/unwind/deferred.c b/kernel/unwind/deferred.c index dc6040aae3ee..5dfd0ac264d1 100644 --- a/kernel/unwind/deferred.c +++ b/kernel/unwind/deferred.c @@ -37,10 +37,6 @@ static inline bool try_assign_cnt(struct unwind_task_info *info, u32 cnt) } #endif -/* Make the cache fit in a 4K page */ -#define UNWIND_MAX_ENTRIES \ - ((SZ_4K - sizeof(struct unwind_cache)) / sizeof(long)) - /* Guards adding to or removing from the list of callbacks */ static DEFINE_MUTEX(callback_mutex); static LIST_HEAD(callbacks); @@ -118,8 +114,7 @@ int unwind_user_faultable(struct unwind_stacktrace *trace) return -EINVAL; if (!info->cache) { - info->cache = kzalloc(struct_size(cache, entries, UNWIND_MAX_ENTRIES), - GFP_KERNEL); + info->cache = kzalloc(sizeof(*cache), GFP_KERNEL); if (!info->cache) return -ENOMEM; } -- Steve
