linux-kernel - [PATCH RT 1/9] mm, zsmalloc: Convert zsmalloc_handle.lock to spinlock

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Date:   Mon, 15 Nov 2021 18:33:40 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>, Daniel Wagner <wagi@...om.org>,
        Tom Zanussi <zanussi@...nel.org>,
        "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>,
        stable-rt@...r.kernel.org, Mike Galbraith <efault@....de>
Subject: [PATCH RT 1/9] mm, zsmalloc: Convert zsmalloc_handle.lock to spinlock_t

5.10.78-rt56-rc1 stable review patch.
If anyone has any objections, please let me know.

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

From: Mike Galbraith <efault@....de>

local_lock_t becoming a synonym of spinlock_t had consequences for the RT
mods to zsmalloc, which were taking a mutex while holding a local_lock,
inspiring a lockdep "BUG: Invalid wait context" gripe.

Converting zsmalloc_handle.lock to a spinlock_t restored lockdep silence.

Cc: stable-rt@...r.kernel.org
Signed-off-by: Mike Galbraith <efault@....de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 mm/zsmalloc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 277d426c881f..3595c1644135 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -82,7 +82,7 @@
 
 struct zsmalloc_handle {
 	unsigned long addr;
-	struct mutex lock;
+	spinlock_t lock;
 };
 
 #define ZS_HANDLE_ALLOC_SIZE (sizeof(struct zsmalloc_handle))
@@ -370,7 +370,7 @@ static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
 	if (p) {
 		struct zsmalloc_handle *zh = p;
 
-		mutex_init(&zh->lock);
+		spin_lock_init(&zh->lock);
 	}
 #endif
 	return (unsigned long)p;
@@ -930,7 +930,7 @@ static inline int testpin_tag(unsigned long handle)
 #ifdef CONFIG_PREEMPT_RT
 	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
 
-	return mutex_is_locked(&zh->lock);
+	return spin_is_locked(&zh->lock);
 #else
 	return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle);
 #endif
@@ -941,7 +941,7 @@ static inline int trypin_tag(unsigned long handle)
 #ifdef CONFIG_PREEMPT_RT
 	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
 
-	return mutex_trylock(&zh->lock);
+	return spin_trylock(&zh->lock);
 #else
 	return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
 #endif
@@ -952,7 +952,7 @@ static void pin_tag(unsigned long handle) __acquires(bitlock)
 #ifdef CONFIG_PREEMPT_RT
 	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
 
-	return mutex_lock(&zh->lock);
+	return spin_lock(&zh->lock);
 #else
 	bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
 #endif
@@ -963,7 +963,7 @@ static void unpin_tag(unsigned long handle) __releases(bitlock)
 #ifdef CONFIG_PREEMPT_RT
 	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
 
-	return mutex_unlock(&zh->lock);
+	return spin_unlock(&zh->lock);
 #else
 	bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
 #endif
-- 
2.33.0