The patch titled
Subject: lib/stackdepot: include gfp.h
has been added to the -mm tree. Its filename is
lib-stackdepot-include-gfph.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/lib-stackdepot-include-gfph.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/lib-stackdepot-include-gfph.patch
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------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
Subject: lib/stackdepot: include gfp.h
Patch series "stackdepot, kasan, workqueue: Avoid expanding stackdepot slabs when holding raw_spin_lock", v2.
Shuah Khan reported [1]:
| When CONFIG_PROVE_RAW_LOCK_NESTING=y and CONFIG_KASAN are enabled,
| kasan_record_aux_stack() runs into "BUG: Invalid wait context" when
| it tries to allocate memory attempting to acquire spinlock in page
| allocation code while holding workqueue pool raw_spinlock.
|
| There are several instances of this problem when block layer tries
| to __queue_work(). Call trace from one of these instances is below:
|
| kblockd_mod_delayed_work_on()
| mod_delayed_work_on()
| __queue_delayed_work()
| __queue_work() (rcu_read_lock, raw_spin_lock pool->lock held)
| insert_work()
| kasan_record_aux_stack()
| kasan_save_stack()
| stack_depot_save()
| alloc_pages()
| __alloc_pages()
| get_page_from_freelist()
| rm_queue()
| rm_queue_pcplist()
| local_lock_irqsave(&pagesets.lock, flags);
| [ BUG: Invalid wait context triggered ]
PROVE_RAW_LOCK_NESTING is pointing out that (on RT kernels) the locking
rules are being violated. More generally, memory is being allocated from
a non-preemptive context (raw_spin_lock'd c-s) where it is not allowed.
To properly fix this, we must prevent stackdepot from replenishing its
"stack slab" pool if memory allocations cannot be done in the current
context: it's a bug to use either GFP_ATOMIC nor GFP_NOWAIT in certain
non-preemptive contexts, including raw_spin_locks (see gfp.h and
ab00db216c9c7).
The only downside is that saving a stack trace may fail if: stackdepot
runs out of space AND the same stack trace has not been recorded before.
I expect this to be unlikely, and a simple experiment (boot the kernel)
didn't result in any failure to record stack trace from insert_work().
The series includes a few minor fixes to stackdepot that I noticed in
preparing the series. It then introduces __stack_depot_save(), which
exposes the option to force stackdepot to not allocate any memory.
Finally, KASAN is changed to use the new stackdepot interface and provide
kasan_record_aux_stack_noalloc(), which is then used by workqueue code.
[1] https://lkml.kernel.org/r/20210902200134.25603-1-skhan@xxxxxxxxxxxxxxxxxxx
This patch (of 6):
<linux/stackdepot.h> refers to gfp_t, but doesn't include gfp.h.
Fix it by including <linux/gfp.h>.
Link: https://lkml.kernel.org/r/20210913112609.2651084-1-elver@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210913112609.2651084-2-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Tested-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Acked-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Walter Wu <walter-zh.wu@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
Cc: Taras Madan <tarasmadan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/stackdepot.h | 2 ++
1 file changed, 2 insertions(+)
--- a/include/linux/stackdepot.h~lib-stackdepot-include-gfph
+++ a/include/linux/stackdepot.h
@@ -11,6 +11,8 @@
#ifndef _LINUX_STACKDEPOT_H
#define _LINUX_STACKDEPOT_H
+#include <linux/gfp.h>
+
typedef u32 depot_stack_handle_t;
depot_stack_handle_t stack_depot_save(unsigned long *entries,
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
kasan-fix-kconfig-check-of-cc_has_working_nosanitize_address.patch
lib-stackdepot-include-gfph.patch
lib-stackdepot-remove-unused-function-argument.patch
lib-stackdepot-introduce-__stack_depot_save.patch
kasan-common-provide-can_alloc-in-kasan_save_stack.patch
kasan-generic-introduce-kasan_record_aux_stack_noalloc.patch
workqueue-kasan-avoid-alloc_pages-when-recording-stack.patch
mm-fix-data-race-in-pagepoisoned.patch
