Re: [PATCH v2] rcu: Handle failure of memory allocation functions

["Paul E. McKenney" <paulmck@xxxxxxxxxx>]

On Sun, Jun 12, 2022 at 02:48:25PM +0800, Li Qiong wrote:
> Add warning when these functions (eg:kmalloc,vmalloc) fail, handle the
> failure.
> 
> Signed-off-by: Li Qiong <liqiong@xxxxxxxxxxxx>

Queued for review and testing with a bit of wordsmithing, thank you!

Please see below to check whether I messed something up.

							Thanx, Paul

------------------------------------------------------------------------

commit 19deffcffe66991c9a9e435ae90b16b97b83e4c1
Author: Li Qiong <liqiong@xxxxxxxxxxxx>
Date:   Sun Jun 12 14:48:25 2022 +0800

    rcu: Handle failure of memory allocation functions
    
    This commit adds warnings and ends the mem_dump_obj() test when allocation
    functions (kmalloc(), vmalloc(), ...) fail.
    
    Signed-off-by: Li Qiong <liqiong@xxxxxxxxxxxx>
    Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 21470ebb15eb4..ccc1af23dc1f2 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2051,7 +2051,13 @@ static void rcu_torture_mem_dump_obj(void)
 	static int z;
 
 	kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
+	if (WARN_ON_ONCE(!kcp))
+		return;
 	rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
+	if (WARN_ON_ONCE(!rhp)) {
+		kmem_cache_destroy(kcp);
+		return;
+	}
 	pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
 	pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
 	mem_dump_obj(ZERO_SIZE_PTR);
@@ -2068,6 +2074,8 @@ static void rcu_torture_mem_dump_obj(void)
 	kmem_cache_free(kcp, rhp);
 	kmem_cache_destroy(kcp);
 	rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
+	if (WARN_ON_ONCE(!rhp))
+		return;
 	pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
 	pr_alert("mem_dump_obj(kmalloc %px):", rhp);
 	mem_dump_obj(rhp);
@@ -2075,6 +2083,8 @@ static void rcu_torture_mem_dump_obj(void)
 	mem_dump_obj(&rhp->func);
 	kfree(rhp);
 	rhp = vmalloc(4096);
+	if (WARN_ON_ONCE(!rhp))
+		return;
 	pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
 	pr_alert("mem_dump_obj(vmalloc %px):", rhp);
 	mem_dump_obj(rhp);