* [PATCH] mm/swapfile: Do not sleep with a spin lock held
@ 2020-12-02 15:15 Qian Cai
2020-12-02 23:15 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: Qian Cai @ 2020-12-02 15:15 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, linux-kernel, Qian Cai
We can't call kvfree() with a spin lock held, so defer it.
Signed-off-by: Qian Cai <qcai@redhat.com>
---
mm/swapfile.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index c4a613688a17..d58361109066 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2867,6 +2867,7 @@ late_initcall(max_swapfiles_check);
static struct swap_info_struct *alloc_swap_info(void)
{
struct swap_info_struct *p;
+ struct swap_info_struct *defer = NULL;
unsigned int type;
int i;
@@ -2895,7 +2896,7 @@ static struct swap_info_struct *alloc_swap_info(void)
smp_wmb();
WRITE_ONCE(nr_swapfiles, nr_swapfiles + 1);
} else {
- kvfree(p);
+ defer = p;
p = swap_info[type];
/*
* Do not memset this entry: a racing procfs swap_next()
@@ -2908,6 +2909,7 @@ static struct swap_info_struct *alloc_swap_info(void)
plist_node_init(&p->avail_lists[i], 0);
p->flags = SWP_USED;
spin_unlock(&swap_lock);
+ kvfree(defer);
spin_lock_init(&p->lock);
spin_lock_init(&p->cont_lock);
--
2.28.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/swapfile: Do not sleep with a spin lock held
2020-12-02 15:15 [PATCH] mm/swapfile: Do not sleep with a spin lock held Qian Cai
@ 2020-12-02 23:15 ` Andrew Morton
2020-12-02 23:39 ` Qian Cai
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2020-12-02 23:15 UTC (permalink / raw)
To: Qian Cai; +Cc: linux-mm, linux-kernel
On Wed, 2 Dec 2020 10:15:49 -0500 Qian Cai <qcai@redhat.com> wrote:
> We can't call kvfree() with a spin lock held, so defer it.
>
Fixes: 873d7bcfd066 ("mm/swapfile.c: use kvzalloc for swap_info_struct allocatio
n")
Do you think it's worth a cc:stable? IOW, is this known to ever
produce a warning?
(If not, why did we need 873d7bcfd066??)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/swapfile: Do not sleep with a spin lock held
2020-12-02 23:15 ` Andrew Morton
@ 2020-12-02 23:39 ` Qian Cai
0 siblings, 0 replies; 3+ messages in thread
From: Qian Cai @ 2020-12-02 23:39 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, linux-kernel
On Wed, 2020-12-02 at 15:15 -0800, Andrew Morton wrote:
> On Wed, 2 Dec 2020 10:15:49 -0500 Qian Cai <qcai@redhat.com> wrote:
>
> > We can't call kvfree() with a spin lock held, so defer it.
> >
>
> Fixes: 873d7bcfd066 ("mm/swapfile.c: use kvzalloc for swap_info_struct
> allocatio
> n")
>
> Do you think it's worth a cc:stable? IOW, is this known to ever
> produce a warning?
Yes, it did trigger a might_sleep() warning.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-02 23:40 UTC | newest]
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