+ mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch added to -mm tree

+ mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch added to -mm tree

[akpm]

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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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Manfred Spraul <manfred@colorfullife.com>
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@colorfullife.com
Link: https://lore.kernel.org/all/20211222081026.484058-1-chi.minghao@zte.com.cn/
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reported-by: Minghao Chi <chi.minghao@zte.com.cn>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: CGEL ZTE <cgel.zte@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <1vier1@web.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@colorfullife.com are

mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch

Re: + mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch added to -mm tree

[Manfred Spraul]

Hi Andrew,

On 1/27/22 03:55, akpm@linux-foundation.org wrote:
> 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

Please drop and replace with

https://marc.info/?l=linux-kernel&m=164132744522325&w=2

If I should rediff/resend, just ping me.

--

     Manfred

Re: + mm-utilc-make-kvfree-safe-for-calling-while-holding-spinlocks.patch added to -mm tree

[Andrew Morton]

On Thu, 27 Jan 2022 16:45:58 +0100 Manfred Spraul <manfred@colorfullife.com> wrote:

> Hi Andrew,
> 
> On 1/27/22 03:55, akpm@linux-foundation.org wrote:
> > 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
> 
> Please drop and replace with
> 
> https://marc.info/?l=linux-kernel&m=164132744522325&w=2
> 

Ah, OK, that's been in -mm and -next for a month.  I didn't send it
upstream because it wasn't clear to me which way we're going.  I'll add
cc:stable and send it to Linus this week or next.