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authorHuang Ying <ying.huang@intel.com>2017-03-20 09:26:42 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-22 00:13:19 +0300
commit093b995e3b55a0ae0670226ddfcb05bfbf0099ae (patch)
tree4608884f3449e11b750c8db47247a07b0b1c863d
parent1f02071358301e376f5a54e40531db37a1d7c7ab (diff)
downloadlinux-093b995e3b55a0ae0670226ddfcb05bfbf0099ae.tar.xz
mm, swap: Remove WARN_ON_ONCE() in free_swap_slot()
Before commit 452b94b8c8c7 ("mm/swap: don't BUG_ON() due to uninitialized swap slot cache"), the following bug is reported, ------------[ cut here ]------------ kernel BUG at mm/swap_slots.c:270! invalid opcode: 0000 [#1] SMP CPU: 5 PID: 1745 Comm: (sd-pam) Not tainted 4.11.0-rc1-00243-g24c534bb161b #1 Hardware name: System manufacturer System Product Name/Z170-K, BIOS 1803 05/06/2016 RIP: 0010:free_swap_slot+0xba/0xd0 Call Trace: swap_free+0x36/0x40 do_swap_page+0x360/0x6d0 __handle_mm_fault+0x880/0x1080 handle_mm_fault+0xd0/0x240 __do_page_fault+0x232/0x4d0 do_page_fault+0x20/0x70 page_fault+0x22/0x30 ---[ end trace aefc9ede53e0ab21 ]--- This is raised by the BUG_ON(!swap_slot_cache_initialized) in free_swap_slot(). This is incorrect, because even if the swap slots cache fails to be initialized, the swap should operate properly without the swap slots cache. And the use_swap_slot_cache check later in the function will protect the uninitialized swap slots cache case. In commit 452b94b8c8c7, the BUG_ON() is replaced by WARN_ON_ONCE(). In the patch, the WARN_ON_ONCE() is removed too. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/swap_slots.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 7ebb23836f68..b1ccb58ad397 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -267,8 +267,6 @@ int free_swap_slot(swp_entry_t entry)
{
struct swap_slots_cache *cache;
- WARN_ON_ONCE(!swap_slot_cache_initialized);
-
cache = &get_cpu_var(swp_slots);
if (use_swap_slot_cache && cache->slots_ret) {
spin_lock_irq(&cache->free_lock);