The patch titled
Subject: mm/util.c: make kvfree() safe for calling while holding spinlocks
has been added to the -mm tree. Its filename is
mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch
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------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: mm/util.c: make kvfree() safe for calling while holding spinlocks
One codepath in find_alloc_undo() calls kvfree() while holding a spinlock.
Since vfree() can sleep this is a bug.
Previously, the code path used kfree(), and kfree() is safe to be called
while holding a spinlock.
Minghao proposed to fix this by updating find_alloc_undo().
Alternate proposal to fix this: Instead of changing find_alloc_undo(),
change kvfree() so that the same rules as for kfree() apply: Having
different rules for kfree() and kvfree() just asks for bugs.
Disadvantage: Releasing vmalloc'ed memory will be delayed a bit.
Link: https://lkml.kernel.org/r/20211222194828.15320-1-manfred@xxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/20211222081026.484058-1-chi.minghao@xxxxxxxxxx/
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Reported-by: Zeal Robot <zealci@xxxxxxxxxx>
Reported-by: Minghao Chi <chi.minghao@xxxxxxxxxx>
Cc: Vasily Averin <vvs@xxxxxxxxxxxxx>
Cc: CGEL ZTE <cgel.zte@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Bhaskar Chowdhury <unixbhaskar@xxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Uladzislau Rezki <urezki@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: <1vier1@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/util.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/util.c~mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks
+++ a/mm/util.c
@@ -603,12 +603,12 @@ EXPORT_SYMBOL(kvmalloc_node);
* It is slightly more efficient to use kfree() or vfree() if you are certain
* that you know which one to use.
*
- * Context: Either preemptible task context or not-NMI interrupt.
+ * Context: Any context except NMI interrupt.
*/
void kvfree(const void *addr)
{
if (is_vmalloc_addr(addr))
- vfree(addr);
+ vfree_atomic(addr);
else
kfree(addr);
}
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch
