From 3bd4e0ac61b2fd87d64572e866f58940d1d5fbdf Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (Microsoft)" Date: Sun, 13 Jul 2025 10:17:27 +0300 Subject: [PATCH] execmem: add fallback for failures in vmalloc(VM_ALLOW_HUGE_VMAP) When execmem populates ROX cache it uses vmalloc(VM_ALLOW_HUGE_VMAP). Although vmalloc falls back to allocating base pages if high order allocation fails, it may happen that it still cannot allocate enough memory. Right now ROX cache is only used by modules and in majority of cases the allocations happen at boot time when there's plenty of free memory, but upcoming enabling ROX cache for ftrace and kprobes would mean that execmem allocations can happen when the system is under memory pressure and a failure to allocate large page worth of memory becomes more likely. Fallback to regular vmalloc() if vmalloc(VM_ALLOW_HUGE_VMAP) fails. Link: https://lkml.kernel.org/r/20250713071730.4117334-6-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Peter Zijlstra (Intel) Cc: Daniel Gomez Cc: Masami Hiramatsu (Google) Cc: Petr Pavlu Cc: Steven Rostedt (Google) Signed-off-by: Andrew Morton --- mm/execmem.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/execmem.c b/mm/execmem.c index c99b299b113c..9abf76a63a79 100644 --- a/mm/execmem.c +++ b/mm/execmem.c @@ -291,6 +291,11 @@ static int execmem_cache_populate(struct execmem_range *range, size_t size) alloc_size = round_up(size, PMD_SIZE); p = execmem_vmalloc(range, alloc_size, PAGE_KERNEL, vm_flags); + if (!p) { + alloc_size = size; + p = execmem_vmalloc(range, alloc_size, PAGE_KERNEL, vm_flags); + } + if (!p) return err; @@ -462,7 +467,7 @@ void *execmem_alloc(enum execmem_type type, size_t size) bool use_cache = range->flags & EXECMEM_ROX_CACHE; vm_flags_t vm_flags = VM_FLUSH_RESET_PERMS; pgprot_t pgprot = range->pgprot; - void *p; + void *p = NULL; size = PAGE_ALIGN(size); -- 2.47.2