mem: fix dynamic hugepage mapping in container

[ upstream commit 9bffc92 ]

Since its introduction in 2018, the SIGBUS handler was never registered,
and all related functions were unused.

A SIGBUS can be received by the application when accessing to hugepages
even if mmap() was successful, This happens especially when running
inside containers when there is not enough hugepages. In this case, we
need to recover. A similar scheme can be found in eal_memory.c.

Fixes: 582bed1 ("mem: support mapping hugepages at runtime")

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: David Marchand <david.marchand@redhat.com>

lib/librte_eal/linux/eal/eal_memalloc.c

@@ -107,7 +107,7 @@ static struct rte_memseg_list local_memsegs[RTE_MAX_MEMSEG_LISTS];
 
 static sigjmp_buf huge_jmpenv;
 
-static void __rte_unused huge_sigbus_handler(int signo __rte_unused)
+static void huge_sigbus_handler(int signo __rte_unused)
 {
 	siglongjmp(huge_jmpenv, 1);
 }
@@ -116,15 +116,15 @@ static void __rte_unused huge_sigbus_handler(int signo __rte_unused)
  * non-static local variable in the stack frame calling sigsetjmp might be
  * clobbered by a call to longjmp.
  */
-static int __rte_unused huge_wrap_sigsetjmp(void)
+static int huge_wrap_sigsetjmp(void)
 {
 	return sigsetjmp(huge_jmpenv, 1);
 }
 
 static struct sigaction huge_action_old;
 static int huge_need_recover;
 
-static void __rte_unused
+static void
 huge_register_sigbus(void)
 {
 	sigset_t mask;
@@ -139,7 +139,7 @@ huge_register_sigbus(void)
 	huge_need_recover = !sigaction(SIGBUS, &action, &huge_action_old);
 }
 
-static void __rte_unused
+static void
 huge_recover_sigbus(void)
 {
 	if (huge_need_recover) {
@@ -565,6 +565,8 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 		mmap_flags = MAP_SHARED | MAP_POPULATE | MAP_FIXED;
 	}
 
+	huge_register_sigbus();
+
 	/*
 	 * map the segment, and populate page tables, the kernel fills
 	 * this segment with zeros if it's a new page.
@@ -640,6 +642,8 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 				__func__);
 #endif
 
+	huge_recover_sigbus();
+
 	ms->addr = addr;
 	ms->hugepage_sz = alloc_sz;
 	ms->len = alloc_sz;
@@ -653,6 +657,7 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 mapped:
 	munmap(addr, alloc_sz);
 unmapped:
+	huge_recover_sigbus();
 	flags = MAP_FIXED;
 	new_addr = eal_get_virtual_area(addr, &alloc_sz, alloc_sz, 0, flags);
 	if (new_addr != addr) {