From 4067196a52278156d18d8d6fa7f43970611b1b49 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Sat, 29 Mar 2025 19:10:29 +0200 Subject: mm/page_alloc: fix deadlock on cpu_hotplug_lock in __accept_page() When the last page in the zone is accepted, __accept_page() calls static_branch_dec(). This function takes cpu_hotplug_lock, which can lead to a deadlock if the allocation occurs during CPU bringup path as _cpu_up() also takes the lock. To prevent this deadlock, defer static_branch_dec() to a workqueue. Call static_branch_dec() only when the workqueue is not yet initialized. Workqueues are initialized before CPU bring up, so this will not conflict with the first scenario. Link: https://lkml.kernel.org/r/20250329171030.3942298-1-kirill.shutemov@linux.intel.com Fixes: 55ad43e8ba0f ("mm: add a helper to accept page") Signed-off-by: Kirill A. Shutemov Reported-by: Srikanth Aithal Tested-by: Srikanth Aithal Cc: Dave Hansen Cc: Ashish Kalra Cc: David Hildenbrand Cc: "Edgecombe, Rick P" Cc: Mel Gorman Cc: "Mike Rapoport (IBM)" Cc: Thomas Lendacky Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/internal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index 50c2f590b2d0..e9695baa5922 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1595,6 +1595,7 @@ unsigned long move_page_tables(struct pagetable_move_control *pmc); #ifdef CONFIG_UNACCEPTED_MEMORY void accept_page(struct page *page); +void unaccepted_cleanup_work(struct work_struct *work); #else /* CONFIG_UNACCEPTED_MEMORY */ static inline void accept_page(struct page *page) { -- cgit v1.2.3