From: <gregkh@linuxfoundation.org>
To: rostedt@goodmis.org,akpm@linux-foundation.org,mark.rutland@arm.com,mathieu.desnoyers@efficios.com,mhiramat@kernel.org
Cc: <stable@vger.kernel.org>
Subject: FAILED: patch "[PATCH] eventfs: Free all of the eventfs_inode after RCU" failed to apply to 6.8-stable tree
Date: Mon, 13 May 2024 17:24:14 +0200 [thread overview]
Message-ID: <2024051314-unwilling-outmatch-c624@gregkh> (raw)
The patch below does not apply to the 6.8-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@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-6.8.y
git checkout FETCH_HEAD
git cherry-pick -x ee4e0379475e4fe723986ae96293e465014fa8d9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024051314-unwilling-outmatch-c624@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..
Possible dependencies:
ee4e0379475e ("eventfs: Free all of the eventfs_inode after RCU")
b63db58e2fa5 ("eventfs/tracing: Add callback for release of an eventfs_inode")
c3137ab6318d ("eventfs: Create eventfs_root_inode to store dentry")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ee4e0379475e4fe723986ae96293e465014fa8d9 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Date: Thu, 2 May 2024 16:08:22 -0400
Subject: [PATCH] eventfs: Free all of the eventfs_inode after RCU
The freeing of eventfs_inode via a kfree_rcu() callback. But the content
of the eventfs_inode was being freed after the last kref. This is
dangerous, as changes are being made that can access the content of an
eventfs_inode from an RCU loop.
Instead of using kfree_rcu() use call_rcu() that calls a function to do
all the freeing of the eventfs_inode after a RCU grace period has expired.
Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.370261163@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcounts")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index f5510e26f0f6..cc8b838bbe62 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -73,6 +73,21 @@ enum {
#define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1)
+static void free_ei_rcu(struct rcu_head *rcu)
+{
+ struct eventfs_inode *ei = container_of(rcu, struct eventfs_inode, rcu);
+ struct eventfs_root_inode *rei;
+
+ kfree(ei->entry_attrs);
+ kfree_const(ei->name);
+ if (ei->is_events) {
+ rei = get_root_inode(ei);
+ kfree(rei);
+ } else {
+ kfree(ei);
+ }
+}
+
/*
* eventfs_inode reference count management.
*
@@ -85,7 +100,6 @@ static void release_ei(struct kref *ref)
{
struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref);
const struct eventfs_entry *entry;
- struct eventfs_root_inode *rei;
WARN_ON_ONCE(!ei->is_freed);
@@ -95,14 +109,7 @@ static void release_ei(struct kref *ref)
entry->release(entry->name, ei->data);
}
- kfree(ei->entry_attrs);
- kfree_const(ei->name);
- if (ei->is_events) {
- rei = get_root_inode(ei);
- kfree_rcu(rei, ei.rcu);
- } else {
- kfree_rcu(ei, rcu);
- }
+ call_rcu(&ei->rcu, free_ei_rcu);
}
static inline void put_ei(struct eventfs_inode *ei)
reply other threads:[~2024-05-13 15:24 UTC|newest]
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