diff options
| author | Max Filippov <jcmvbkbc@gmail.com> | 2022-04-08 13:08:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-04-08 14:20:36 -1000 |
| commit | 66f133ceab7456c789f70a242991ed1b27ba1c3d (patch) | |
| tree | 09890973c01a725e59f84ae45c66946db854aa05 | |
| parent | a04cd1600b831a16625b45226b90a292c8f6e8d9 (diff) | |
| download | linux-66f133ceab7456c789f70a242991ed1b27ba1c3d.tar.bz2 | |
highmem: fix checks in __kmap_local_sched_{in,out}
When CONFIG_DEBUG_KMAP_LOCAL is enabled __kmap_local_sched_{in,out} check
that even slots in the tsk->kmap_ctrl.pteval are unmapped. The slots are
initialized with 0 value, but the check is done with pte_none. 0 pte
however does not necessarily mean that pte_none will return true. e.g.
on xtensa it returns false, resulting in the following runtime warnings:
WARNING: CPU: 0 PID: 101 at mm/highmem.c:627 __kmap_local_sched_out+0x51/0x108
CPU: 0 PID: 101 Comm: touch Not tainted 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13
Call Trace:
dump_stack+0xc/0x40
__warn+0x8f/0x174
warn_slowpath_fmt+0x48/0xac
__kmap_local_sched_out+0x51/0x108
__schedule+0x71a/0x9c4
preempt_schedule_irq+0xa0/0xe0
common_exception_return+0x5c/0x93
do_wp_page+0x30e/0x330
handle_mm_fault+0xa70/0xc3c
do_page_fault+0x1d8/0x3c4
common_exception+0x7f/0x7f
WARNING: CPU: 0 PID: 101 at mm/highmem.c:664 __kmap_local_sched_in+0x50/0xe0
CPU: 0 PID: 101 Comm: touch Tainted: G W 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13
Call Trace:
dump_stack+0xc/0x40
__warn+0x8f/0x174
warn_slowpath_fmt+0x48/0xac
__kmap_local_sched_in+0x50/0xe0
finish_task_switch$isra$0+0x1ce/0x2f8
__schedule+0x86e/0x9c4
preempt_schedule_irq+0xa0/0xe0
common_exception_return+0x5c/0x93
do_wp_page+0x30e/0x330
handle_mm_fault+0xa70/0xc3c
do_page_fault+0x1d8/0x3c4
common_exception+0x7f/0x7f
Fix it by replacing !pte_none(pteval) with pte_val(pteval) != 0.
Link: https://lkml.kernel.org/r/20220403235159.3498065-1-jcmvbkbc@gmail.com
Fixes: 5fbda3ecd14a ("sched: highmem: Store local kmaps in task struct")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/highmem.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/highmem.c b/mm/highmem.c index 0cc0c4da7ed9..1a692997fac4 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -624,7 +624,7 @@ void __kmap_local_sched_out(void) /* With debug all even slots are unmapped and act as guard */ if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { - WARN_ON_ONCE(!pte_none(pteval)); + WARN_ON_ONCE(pte_val(pteval) != 0); continue; } if (WARN_ON_ONCE(pte_none(pteval))) @@ -661,7 +661,7 @@ void __kmap_local_sched_in(void) /* With debug all even slots are unmapped and act as guard */ if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { - WARN_ON_ONCE(!pte_none(pteval)); + WARN_ON_ONCE(pte_val(pteval) != 0); continue; } if (WARN_ON_ONCE(pte_none(pteval))) |