The patch titled Subject: mm/sparse: remove index_init_lock has been removed from the -mm tree. Its filename was mm-sparse-remove-index_init_lock.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx> Subject: mm/sparse: remove index_init_lock sparse_index_init() uses the index_init_lock spinlock to protect root mem_section assignment. The lock is not necessary anymore because the function is called only during boot (during paging init which is executed only from a single CPU) and from the hotplug code (by add_memory() via arch_add_memory()) which uses mem_hotplug_mutex. The lock was introduced by 28ae55c9 ("sparsemem extreme: hotplug preparation") and sparse_index_init() was used only during boot at that time. Later when the hotplug code (and add_memory()) was introduced there was no synchronization so it was possible to online more sections from the same root probably (though I am not 100% sure about that). The first synchronization has been added by 6ad696d2 ("mm: allow memory hotplug and hibernation in the same kernel") which was later replaced by the mem_hotplug_mutex - 20d6c96b ("mem-hotplug: introduce {un}lock_memory_hotplug()"). Let's remove the lock as it is not needed and it makes the code more confusing. [mhocko@xxxxxxx: changelog] Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx> Reviewed-by: Michal Hocko <mhocko@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/sparse.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) diff -puN mm/sparse.c~mm-sparse-remove-index_init_lock mm/sparse.c --- a/mm/sparse.c~mm-sparse-remove-index_init_lock +++ a/mm/sparse.c @@ -77,7 +77,6 @@ static struct mem_section noinline __ini static int __meminit sparse_index_init(unsigned long section_nr, int nid) { - static DEFINE_SPINLOCK(index_init_lock); unsigned long root = SECTION_NR_TO_ROOT(section_nr); struct mem_section *section; int ret = 0; @@ -88,20 +87,9 @@ static int __meminit sparse_index_init(u section = sparse_index_alloc(nid); if (!section) return -ENOMEM; - /* - * This lock keeps two different sections from - * reallocating for the same index - */ - spin_lock(&index_init_lock); - - if (mem_section[root]) { - ret = -EEXIST; - goto out; - } mem_section[root] = section; -out: - spin_unlock(&index_init_lock); + return ret; } #else /* !SPARSEMEM_EXTREME */ _ Patches currently in -mm which might be from shangw@xxxxxxxxxxxxxxxxxx are origin.patch mm-slab-remove-duplicate-check.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html