When VMA based swap readahead is used, which is default if all swap
devices are SSD, swapoff will trigger general protection fault as
follow, because vmf->pmd isn't initialized when calling
swapin_readahead(). This fix could be folded into the patch: mm,
swap: rid swapoff of quadratic complexity in -mm patchset.
general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
CPU: 3 PID: 352 Comm: swapoff Not tainted 4.20.0-rc5-mm1-kvm+ #535
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-1.fc28
04/01/2014
RIP: 0010:swapin_readahead+0xb7/0x39b
Code: ff 01 00 00 40 f6 c7 80 49 0f 45 d0 48 21 d7 48 ba 00 00 00 00 80 88 ff
ff 48 8d 14 f2 48 01 d7 48 ba ff ff ff ff ff ff ff ef <48> 39 17 0f 87 5d 01 00
00 49 8b 95 b0 00 00 00 48 85 d2 75 05 ba
RSP: 0018:ffffc900004c3ca0 EFLAGS: 00010207
RAX: 000055de5d252000 RBX: 000000055de5d252 RCX: 0000000000000003
RDX: efffffffffffffff RSI: 0000000000000052 RDI: 000f0bc11c600290
RBP: ffffc900004c3d30 R08: 000fffffffe00000 R09: ffffc900004c3ea0
R10: ffffc900004c3d50 R11: 0000000000000002 R12: ffffc900004c3da8
R13: ffff88803b71d780 R14: 0000000000000001 R15: ffff88803b71d780
FS: 00007f87c20e02c0(0000) GS:ffff88803e800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a439825398 CR3: 000000003b49a004 CR4: 0000000000360ea0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? list_add_tail_rcu+0x19/0x31
? __lock_acquire+0xd61/0xe1c
? find_held_lock+0x2b/0x6e
? unuse_pte_range+0xe9/0x429
unuse_pte_range+0xe9/0x429
? find_held_lock+0x2b/0x6e
? __lock_is_held+0x40/0x71
try_to_unuse+0x311/0x54b
__do_sys_swapoff+0x254/0x625
? lockdep_hardirqs_off+0x29/0x86
? do_syscall_64+0x12/0x65
do_syscall_64+0x57/0x65
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Signed-off-by: "Huang, Ying" <ying.hu...@intel.com>
Cc: Vineeth Remanan Pillai <vpil...@digitalocean.com>
Cc: Kelley Nielsen <kelley...@gmail.com>
Cc: Rik van Riel <r...@surriel.com>
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Hugh Dickins <hu...@google.com>
---
mm/swapfile.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9ca162cc45dc..7464d0a92869 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1904,6 +1904,7 @@ static int unuse_pte_range(struct vm_area_struct *vma,
pmd_t *pmd,
swap_map = &si->swap_map[offset];
vmf.vma = vma;
vmf.address = addr;
+ vmf.pmd = pmd;
page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf);
if (!page) {
if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD)
--
2.18.1
