Re: [RFC PATCH v8 5/7] KVM: guest_memfd: Add slab-allocated inode cache
From: Shivank Garg <hidden>
Date: 2025-06-29 18:25:37
Also in:
kvm, linux-coco, linux-fsdevel, linux-kselftest, linux-mm, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2025-06-18 · [RFC PATCH v8 5/7] KVM: guest_memfd: Add slab-allocated inode cache · Shivank Garg <hidden>
On 6/24/2025 9:46 AM, Huang, Ying wrote:
Shivank Garg [off-list ref] writes:quoted
+static void kvm_gmem_init_inodecache(void) +{ + kvm_gmem_inode_cachep = kmem_cache_create("kvm_gmem_inode_cache", + sizeof(struct kvm_gmem_inode_info), + 0, SLAB_ACCOUNT, + kvm_gmem_init_inode);Check the return value? And, I'm not a big fan of (logically) one line function encapsulation.quoted
+} + int kvm_gmem_init(struct module *module) { kvm_gmem_fops.owner = module; + kvm_gmem_init_inodecache(); return kvm_gmem_init_mount();kmem_cache_destroy(kvm_gmem_inode_cachep) if kvm_gmem_init_mount() return with error?
Thanks for the feedback, Ying. Good catch on the leak! Regarding the missing error check, I noticed while looking at examples that kernel code is sometimes inconsistent with kmem_cache_create() error handling, but you're right about checking for failures, So I'll handle them properly.
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 7b8c548986d4..8cb83692f7a0 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c@@ -530,20 +530,23 @@ static void kvm_gmem_init_inode(void *foo) inode_init_once(&info->vfs_inode); } -static void kvm_gmem_init_inodecache(void) +int kvm_gmem_init(struct module *module) { + int ret; + + kvm_gmem_fops.owner = module; kvm_gmem_inode_cachep = kmem_cache_create("kvm_gmem_inode_cache", sizeof(struct kvm_gmem_inode_info), 0, SLAB_ACCOUNT, kvm_gmem_init_inode); -} - -int kvm_gmem_init(struct module *module) -{ - kvm_gmem_fops.owner = module; - - kvm_gmem_init_inodecache(); - return kvm_gmem_init_mount(); + if (!kvm_gmem_inode_cachep) + return -ENOMEM; + ret = kvm_gmem_init_mount(); + if (ret) { + kmem_cache_destroy(kvm_gmem_inode_cachep); + return ret; + } + return 0; }
Best Regards, Shivank