The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 17ec2f965344ee3fd6620bef7ef68792f4ac3af0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081210-overhand-panhandle-a07f@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc(a)google.com>
Date: Tue, 10 Jun 2025 16:20:06 -0700
Subject: [PATCH] KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is
supported
Let the guest set DEBUGCTL.RTM_DEBUG if RTM is supported according to the
guest CPUID model, as debug support is supposed to be available if RTM is
supported, and there are no known downsides to letting the guest debug RTM
aborts.
Note, there are no known bug reports related to RTM_DEBUG, the primary
motivation is to reduce the probability of breaking existing guests when a
future change adds a missing consistency check on vmcs12.GUEST_DEBUGCTL
(KVM currently lets L2 run with whatever hardware supports; whoops).
Note #2, KVM already emulates DR6.RTM, and doesn't restrict access to
DR7.RTM.
Fixes: 83c529151ab0 ("KVM: x86: expose Intel cpu new features (HLE, RTM) to guest")
Cc: stable(a)vger.kernel.org
Link: https://lore.kernel.org/r/20250610232010.162191-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc(a)google.com>
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index b7dded3c8113..fa878b136eba 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -419,6 +419,7 @@
#define DEBUGCTLMSR_FREEZE_PERFMON_ON_PMI (1UL << 12)
#define DEBUGCTLMSR_FREEZE_IN_SMM_BIT 14
#define DEBUGCTLMSR_FREEZE_IN_SMM (1UL << DEBUGCTLMSR_FREEZE_IN_SMM_BIT)
+#define DEBUGCTLMSR_RTM_DEBUG BIT(15)
#define MSR_PEBS_FRONTEND 0x000003f7
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4ee6cc796855..311f6fa53b67 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2186,6 +2186,10 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated
(host_initiated || intel_pmu_lbr_is_enabled(vcpu)))
debugctl |= DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI;
+ if (boot_cpu_has(X86_FEATURE_RTM) &&
+ (host_initiated || guest_cpu_cap_has(vcpu, X86_FEATURE_RTM)))
+ debugctl |= DEBUGCTLMSR_RTM_DEBUG;
+
return debugctl;
}
The check for a fast symlink in the presence of only an
external xattr inode is incorrect. If a fast symlink does
not have an xattr block (i_file_acl == 0), but does have
an external xattr inode that increases inode i_blocks, then
the check for a fast symlink will incorrectly fail and
__ext4_iget()->ext4_ind_check_inode() will report the inode
is corrupt when it "validates" i_data[] on the next read:
# ln -s foo /mnt/tmp/bar
# setfattr -h -n trusted.test \
-v "$(yes | head -n 4000)" /mnt/tmp/bar
# umount /mnt/tmp
# mount /mnt/tmp
# ls -l /mnt/tmp
ls: cannot access '/mnt/tmp/bar': Structure needs cleaning
total 4
? l?????????? ? ? ? ? ? bar
# dmesg | tail -1
EXT4-fs error (device dm-8): __ext4_iget:5098:
inode #24578: block 7303014: comm ls: invalid block
(note that "block 7303014" = 0x6f6f66 = "foo" in LE order).
ext4_inode_is_fast_symlink() should check the superblock
EXT4_FEATURE_INCOMPAT_EA_INODE feature flag, not the inode
EXT4_EA_INODE_FL, since the latter is only set on the xattr
inode itself, and not on the inode that uses this xattr.
Cc: stable(a)vger.kernel.org
Fixes: fc82228a5e38 ("ext4: support fast symlinks from ext3 file systems")
Signed-off-by: Andreas Dilger <adilger(a)whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli(a)ddn.com>
Reviewed-by: Alex Zhuravlev <bzzz(a)whamcloud.com>
Reviewed-by: Oleg Drokin <green(a)whamcloud.com>
Reviewed-on: https://review.whamcloud.com/59879
Lustre-bug-id: https://jira.whamcloud.com/browse/LU-19121
---
fs/ext4/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index be9a4cba35fd..caca88521c75 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -146,7 +146,7 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
*/
int ext4_inode_is_fast_symlink(struct inode *inode)
{
- if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
+ if (!ext4_has_feature_ea_inode(inode->i_sb)) {
int ea_blocks = EXT4_I(inode)->i_file_acl ?
EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
--
2.43.5
netlink_attachskb() checks for the socket's read memory allocation
constraints. Firstly, it has:
rmem < READ_ONCE(sk->sk_rcvbuf)
to check if the just increased rmem value fits into the socket's receive
buffer. If not, it proceeds and tries to wait for the memory under:
rmem + skb->truesize > READ_ONCE(sk->sk_rcvbuf)
The checks don't cover the case when skb->truesize + sk->sk_rmem_alloc is
equal to sk->sk_rcvbuf. Thus the function neither successfully accepts
these conditions, nor manages to reschedule the task - and is called in
retry loop for indefinite time which is caught as:
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 0-....: (25999 ticks this GP) idle=ef2/1/0x4000000000000000 softirq=262269/262269 fqs=6212
(t=26000 jiffies g=230833 q=259957)
NMI backtrace for cpu 0
CPU: 0 PID: 22 Comm: kauditd Not tainted 5.10.240 #68
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc42 04/01/2014
Call Trace:
<IRQ>
dump_stack lib/dump_stack.c:120
nmi_cpu_backtrace.cold lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace lib/nmi_backtrace.c:62
rcu_dump_cpu_stacks kernel/rcu/tree_stall.h:335
rcu_sched_clock_irq.cold kernel/rcu/tree.c:2590
update_process_times kernel/time/timer.c:1953
tick_sched_handle kernel/time/tick-sched.c:227
tick_sched_timer kernel/time/tick-sched.c:1399
__hrtimer_run_queues kernel/time/hrtimer.c:1652
hrtimer_interrupt kernel/time/hrtimer.c:1717
__sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113
asm_call_irq_on_stack arch/x86/entry/entry_64.S:808
</IRQ>
netlink_attachskb net/netlink/af_netlink.c:1234
netlink_unicast net/netlink/af_netlink.c:1349
kauditd_send_queue kernel/audit.c:776
kauditd_thread kernel/audit.c:897
kthread kernel/kthread.c:328
ret_from_fork arch/x86/entry/entry_64.S:304
Restore the original behavior of the check which commit in Fixes
accidentally missed when restructuring the code.
Found by Linux Verification Center (linuxtesting.org).
Fixes: ae8f160e7eb2 ("netlink: Fix wraparounds of sk->sk_rmem_alloc.")
Cc: stable(a)vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin(a)ispras.ru>
---
Similar rmem and sk->sk_rcvbuf comparing pattern in
netlink_broadcast_deliver() accepts these values being equal, while
the netlink_dump() case does not - but it goes all the way down to
f9c2288837ba ("netlink: implement memory mapped recvmsg()") and looks
like an irrelevant issue without any real consequences. Though might be
cleaned up if needed.
Updated sk->sk_rmem_alloc vs sk->sk_rcvbuf checks throughout the kernel
diverse in treating the corner case of them being equal.
net/netlink/af_netlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6332a0e06596..0fc3f045fb65 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1218,7 +1218,7 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
nlk = nlk_sk(sk);
rmem = atomic_add_return(skb->truesize, &sk->sk_rmem_alloc);
- if ((rmem == skb->truesize || rmem < READ_ONCE(sk->sk_rcvbuf)) &&
+ if ((rmem == skb->truesize || rmem <= READ_ONCE(sk->sk_rcvbuf)) &&
!test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
netlink_skb_set_owner_r(skb, sk);
return 0;
--
2.50.1
Buffer bouncing is needed only when memory exists above the lowmem region,
i.e., when max_low_pfn < max_pfn. The previous check (max_low_pfn >=
max_pfn) was inverted and prevented bouncing when it could actually be
required.
Note that bouncing depends on CONFIG_HIGHMEM, which is typically enabled
on 32-bit ARM where not all memory is permanently mapped into the kernel’s
lowmem region.
Branch-Specific Note:
This fix is specific to this branch (6.6.y) only.
In the upstream “tip” kernel, bounce buffer support for highmem pages
was completely removed after kernel version 6.12. Therefore, this
modification is not possible or relevant in the tip branch.
Fixes: 9bb33f24abbd0 ("block: refactor the bounce buffering code")
Cc: stable(a)vger.kernel.org
Signed-off-by: Hardeep Sharma <quic_hardshar(a)quicinc.com>
---
block/blk.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk.h b/block/blk.h
index 67915b04b3c1..f8a1d64be5a2 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -383,7 +383,7 @@ static inline bool blk_queue_may_bounce(struct request_queue *q)
{
return IS_ENABLED(CONFIG_BOUNCE) &&
q->limits.bounce == BLK_BOUNCE_HIGH &&
- max_low_pfn >= max_pfn;
+ max_low_pfn < max_pfn;
}
static inline struct bio *blk_queue_bounce(struct bio *bio,
--
2.25.1