diff mbox series

[1/2,xarry] :Fixed an issue with memory allocated using the GFP_KERNEL flag in spinlocks

Message ID 20201104023213.760-1-xiaofeng.yan2012@gmail.com (mailing list archive)
State New, archived
Headers show
Series [1/2,xarry] :Fixed an issue with memory allocated using the GFP_KERNEL flag in spinlocks | expand

Commit Message

xiaofeng.yan Nov. 4, 2020, 2:32 a.m. UTC 
From: "xiaofeng.yan" <yanxiaofeng7@jd.com>

function xa_store_irq() has a spinlock as follows:
 xa_lock_irq()
   -->spin_lock_irq(&(xa)->xa_lock)
GFP_KERNEL flag could cause sleep.
So change GFP_KERNEL to  GFP_ATOMIC and Romve "gfp_t gfp" in function
static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
                void *entry, gfp_t gfp)

Signed-off-by: xiaofeng.yan <yanxiaofeng7@jd.com>
---
 include/linux/xarray.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

Matthew Wilcox Nov. 4, 2020, 2:36 a.m. UTC | #1 
On Wed, Nov 04, 2020 at 10:32:12AM +0800, xiaofeng.yan wrote:
>  	xa_lock_irq(xa);
> -	curr = __xa_store(xa, index, entry, gfp);
> +	curr = __xa_store(xa, index, entry, GFP_ATOMIC);
>  	xa_unlock_irq(xa);

You haven't actually seen a bug, have you?  You just read the code
wrongly.

void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
...
        } while (__xas_nomem(&xas, gfp));
...
        if (gfpflags_allow_blocking(gfp)) {
                xas_unlock_type(xas, lock_type);
                xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
                xas_lock_type(xas, lock_type);
diff mbox series

Patch

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 92c0160b3352..aeaf97d5642f 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -595,7 +595,6 @@  static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
  * @xa: XArray.
  * @index: Index into array.
  * @entry: New entry.
- * @gfp: Memory allocation flags.
  *
  * This function is like calling xa_store() except it disables interrupts
  * while holding the array lock.
@@ -605,12 +604,12 @@  static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
  * Return: The old entry at this index or xa_err() if an error happened.
  */
 static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
-		void *entry, gfp_t gfp)
+		void *entry)
 {
 	void *curr;
 
 	xa_lock_irq(xa);
-	curr = __xa_store(xa, index, entry, gfp);
+	curr = __xa_store(xa, index, entry, GFP_ATOMIC);
 	xa_unlock_irq(xa);
 
 	return curr;