[PATCH 4.19 18/37] mt7601u: fix rx buffer refcounting

Greg Kroah-Hartman
2021-02-02T14:58:23Z

From: Lorenzo Bianconi <lorenzo@kernel.org>

commit d24c790577ef01bfa01da2b131313a38c843a634 upstream.

Fix the following crash due to erroneous page refcounting:

[ 32.445919] BUG: Bad page state in process swapper/1 pfn:11f65a
[ 32.447409] page:00000000938f0632 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x11f65a
[ 32.449605] flags: 0x8000000000000000()
[ 32.450421] raw: 8000000000000000 ffffffff825b0148 ffffea00045ae988 0000000000000000
[ 32.451795] raw: 0000000000000000 0000000000000001 00000000ffffff7f 0000000000000000
[ 32.452999] page dumped because: nonzero mapcount
[ 32.453888] Modules linked in:
[ 32.454492] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.11.0-rc2+ #1976
[ 32.455695] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-1.fc33 04/01/2014
[ 32.457157] Call Trace:
[ 32.457636] <IRQ>
[ 32.457993] dump_stack+0x77/0x97
[ 32.458576] bad_page.cold+0x65/0x96
[ 32.459198] get_page_from_freelist+0x46a/0x11f0
[ 32.460008] __alloc_pages_nodemask+0x10a/0x2b0
[ 32.460794] mt7601u_rx_tasklet+0x651/0x720
[ 32.461505] tasklet_action_common.constprop.0+0x6b/0xd0
[ 32.462343] __do_softirq+0x152/0x46c
[ 32.462928] asm_call_irq_on_stack+0x12/0x20
[ 32.463610] </IRQ>
[ 32.463953] do_softirq_own_stack+0x5b/0x70
[ 32.464582] irq_exit_rcu+0x9f/0xe0
[ 32.465028] common_interrupt+0xae/0x1a0
[ 32.465536] asm_common_interrupt+0x1e/0x40
[ 32.466071] RIP: 0010:default_idle+0x18/0x20
[ 32.468981] RSP: 0018:ffffc90000077f00 EFLAGS: 00000246
[ 32.469648] RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
[ 32.470550] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff81aac3dd
[ 32.471463] RBP: ffff88810022ab00 R08: 0000000000000001 R09: 0000000000000001
[ 32.472335] R10: 0000000000000046 R11: 0000000000005aa0 R12: 0000000000000000
[ 32.473235] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 32.474139] ? default_idle_call+0x4d/0x200
[ 32.474681] default_idle_call+0x74/0x200
[ 32.475192] do_idle+0x1d5/0x250
[ 32.475612] cpu_startup_entry+0x19/0x20
[ 32.476114] secondary_startup_64_no_verify+0xb0/0xbb
[ 32.476765] Disabling lock debugging due to kernel taint

Fixes: c869f77d6abb ("add mt7601u driver")
Co-developed-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/62b2380c8c2091834cfad05e1059b55f945bd114.1610643952.git.lorenzo@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/mediatek/mt7601u/dma.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/net/wireless/mediatek/mt7601u/dma.c
+++ b/drivers/net/wireless/mediatek/mt7601u/dma.c
@@ -160,8 +160,7 @@ mt7601u_rx_process_entry(struct mt7601u_

if (new_p) {
/* we have one extra ref from the allocator */
- __free_pages(e->p, MT_RX_ORDER);
-
+ put_page(e->p);
e->p = new_p;
}
}