Patch "KVM: Fix lockdep false negative during host resume" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: Fix lockdep false negative during host resume

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-fix-lockdep-false-negative-during-host-resume.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 133edb71da2797d6bd1c9b17e80209cca680b8c0
Author: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Date:   Tue Feb 15 02:15:42 2022 -0800

    KVM: Fix lockdep false negative during host resume
    
    [ Upstream commit 4cb9a998b1ce25fad74a82f5a5c45a4ef40de337 ]
    
    I saw the below splatting after the host suspended and resumed.
    
       WARNING: CPU: 0 PID: 2943 at kvm/arch/x86/kvm/../../../virt/kvm/kvm_main.c:5531 kvm_resume+0x2c/0x30 [kvm]
       CPU: 0 PID: 2943 Comm: step_after_susp Tainted: G        W IOE     5.17.0-rc3+ #4
       RIP: 0010:kvm_resume+0x2c/0x30 [kvm]
       Call Trace:
        <TASK>
        syscore_resume+0x90/0x340
        suspend_devices_and_enter+0xaee/0xe90
        pm_suspend.cold+0x36b/0x3c2
        state_store+0x82/0xf0
        kernfs_fop_write_iter+0x1b6/0x260
        new_sync_write+0x258/0x370
        vfs_write+0x33f/0x510
        ksys_write+0xc9/0x160
        do_syscall_64+0x3b/0xc0
        entry_SYSCALL_64_after_hwframe+0x44/0xae
    
    lockdep_is_held() can return -1 when lockdep is disabled which triggers
    this warning. Let's use lockdep_assert_not_held() which can detect
    incorrect calls while holding a lock and it also avoids false negatives
    when lockdep is disabled.
    
    Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
    Message-Id: <1644920142-81249-1-git-send-email-wanpengli@xxxxxxxxxxx>
    Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f8b42e19bc77..fcceb8443aa9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5417,9 +5417,7 @@ static int kvm_suspend(void)
 static void kvm_resume(void)
 {
 	if (kvm_usage_count) {
-#ifdef CONFIG_LOCKDEP
-		WARN_ON(lockdep_is_held(&kvm_count_lock));
-#endif
+		lockdep_assert_not_held(&kvm_count_lock);
 		hardware_enable_nolock(NULL);
 	}
 }