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Date: Thu, 20 Jul 2023 11:50:52 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Mark Brown <broonie@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org
Subject: Re: Traceback with CONFIG_REGMAP_KUNIT=y+CONFIG_DEBUG_ATOMIC_SLEEP=y
On Wed, Jul 19, 2023 at 03:37:54PM -0700, Guenter Roeck wrote:
> Hi,
>
> when booting images with both CONFIG_REGMAP_KUNIT and
> CONFIG_DEBUG_ATOMIC_SLEEP enabled, I get the following backtrace.
>
> [ 4.994957] # Subtest: regmap
> [ 4.995067] 1..14
> [ 4.995190] KTAP version 1
> [ 4.995308] # Subtest: basic_read_write
> [ 4.999402] ok 1 none
> [ 5.003028] ok 2 flat
> [ 5.005510] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
> [ 5.005960] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 117, name: kunit_try_catch
> [ 5.006219] preempt_count: 1, expected: 0
> [ 5.006414] 1 lock held by kunit_try_catch/117:
> [ 5.006590] #0: 833b9010 (regmap_kunit:86:(config)->lock){....}-{2:2}, at: regmap_lock_spinlock+0x14/0x1c
> [ 5.007493] irq event stamp: 162
> [ 5.007627] hardirqs last enabled at (161): [<80786738>] crng_make_state+0x1a0/0x294
> [ 5.007871] hardirqs last disabled at (162): [<80c531ec>] _raw_spin_lock_irqsave+0x7c/0x80
> [ 5.008119] softirqs last enabled at (0): [<801110ac>] copy_process+0x810/0x2138
> [ 5.008356] softirqs last disabled at (0): [<00000000>] 0x0
> [ 5.008688] CPU: 0 PID: 117 Comm: kunit_try_catch Tainted: G N 6.4.4-rc3-g0e8d2fdfb188 #1
> [ 5.009011] Hardware name: Generic DT based system
> [ 5.009277] unwind_backtrace from show_stack+0x18/0x1c
> [ 5.009497] show_stack from dump_stack_lvl+0x38/0x5c
> [ 5.009676] dump_stack_lvl from __might_resched+0x188/0x2d0
> [ 5.009860] __might_resched from __kmem_cache_alloc_node+0x1dc/0x25c
> [ 5.010061] __kmem_cache_alloc_node from kmalloc_trace+0x30/0xc8
> [ 5.010254] kmalloc_trace from regcache_rbtree_write+0x26c/0x468
> [ 5.010446] regcache_rbtree_write from _regmap_write+0x88/0x140
> [ 5.010634] _regmap_write from regmap_write+0x44/0x68
> [ 5.010803] regmap_write from basic_read_write+0x8c/0x270
> [ 5.010980] basic_read_write from kunit_try_run_case+0x48/0xa0
> [ 5.011170] kunit_try_run_case from kunit_generic_run_threadfn_adapter+0x1c/0x28
> [ 5.011396] kunit_generic_run_threadfn_adapter from kthread+0xf8/0x120
> [ 5.011603] kthread from ret_from_fork+0x14/0x3c
> [ 5.011801] Exception stack(0x881a5fb0 to 0x881a5ff8)
> [ 5.012024] 5fa0: 00000000 00000000 00000000 00000000
> [ 5.012269] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [ 5.012502] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [ 5.014546] ok 3 rbtree
> [ 5.018988] ok 4 maple
>
> This isn't surprising given that the regmap code allocates rbcache nodes
> with GFP_KERNEL and the regmap configuration results in using spinlock
> to lock regmap accesses.
>
> I'll be happy to submit a patch to fix the problem, but I would need
> some advice. I could
>
> - Update the unit test regmap configuration to avoid using
> spinlock as locking mechanism for rbtree tests.
> That would work, but fail to catch situations where this happens
> in the real world.
> - Use a different method to allocate memory in regcache_rbtree_node_alloc().
> - Replace GFP_KERNEL with GFP_NOWAIT or GFP_KERNEL | __GFP_NOWARN (?)
> or something else, possibly only if gfpflags_allow_blocking() is false
__GFP_NOWARN is only about allocation failure, not sleeping. I would
have thought it should be.
diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index fabf87058d80..d94e25120f2f 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -187,7 +187,7 @@ static int regcache_rbtree_init(struct regmap *map)
int i;
int ret;
- map->cache = kmalloc(sizeof *rbtree_ctx, GFP_KERNEL);
+ map->cache = kmalloc(sizeof *rbtree_ctx, map->alloc_flags);
if (!map->cache)
return -ENOMEM;
@@ -277,7 +277,7 @@ static int regcache_rbtree_insert_to_block(struct regmap *map,
blk = krealloc(rbnode->block,
blklen * map->cache_word_size,
- GFP_KERNEL);
+ map->alloc_flags);
if (!blk)
return -ENOMEM;
@@ -286,7 +286,7 @@ static int regcache_rbtree_insert_to_block(struct regmap *map,
if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
present = krealloc(rbnode->cache_present,
BITS_TO_LONGS(blklen) * sizeof(*present),
- GFP_KERNEL);
+ map->alloc_flags);
if (!present)
return -ENOMEM;
@@ -320,7 +320,7 @@ regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
const struct regmap_range *range;
int i;
- rbnode = kzalloc(sizeof(*rbnode), GFP_KERNEL);
+ rbnode = kzalloc(sizeof(*rbnode), map->alloc_flags);
if (!rbnode)
return NULL;
@@ -346,13 +346,13 @@ regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
}
rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
- GFP_KERNEL);
+ map->alloc_flags);
if (!rbnode->block)
goto err_free;
rbnode->cache_present = kcalloc(BITS_TO_LONGS(rbnode->blklen),
sizeof(*rbnode->cache_present),
- GFP_KERNEL);
+ map->alloc_flags);
if (!rbnode->cache_present)
goto err_free_block;
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