From: Qian Cai qcai@redhat.com Subject: mm/swapfile: do not sleep with a spin lock held

We can't call kvfree() with a spin lock held, so defer it. Fixes a might_sleep() runtime warning.

Link: https://lkml.kernel.org/r/20201202151549.10350-1-qcai@redhat.com Fixes: 873d7bcfd066 ("mm/swapfile.c: use kvzalloc for swap_info_struct allocation") Signed-off-by: Qian Cai qcai@redhat.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Hugh Dickins hughd@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/swapfile.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/swapfile.c~mm-swapfile-do-not-sleep-with-a-spin-lock-held +++ a/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_sw 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_sw 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);

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