On 11/20/23 19:49, Mark Brown wrote:
> On Thu, Nov 02, 2023 at 03:23:27AM +0000, chengming.zhou@xxxxxxxxx wrote:
>> From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
>>
>> Now we will freeze slabs when moving them out of node partial list to
>> cpu partial list, this method needs two cmpxchg_double operations:
>>
>> 1. freeze slab (acquire_slab()) under the node list_lock
>> 2. get_freelist() when pick used in ___slab_alloc()
>
> Recently -next has been failing to boot on a Raspberry Pi 3 with an arm
> multi_v7_defconfig and a NFS rootfs, a bisect appears to point to this
> patch (in -next as c8d312e039030edab25836a326bcaeb2a3d4db14) as having
> introduced the issue. I've included the full bisect log below.
>
> When we see problems we see RCU stalls while logging in, for example:
Can you try this, please?
----8<----
>From 000030c1ff055ef6a2ca624d0142f08f3ef19d51 Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@xxxxxxx>
Date: Wed, 22 Nov 2023 10:32:41 +0100
Subject: [PATCH] mm/slub: try to fix hangs without cmpxchg64/128
If we don't have cmpxchg64/128 and resort to slab_lock()/slab_unlock()
which uses PG_locked, we can get RMW with the newly introduced
slab_set/clear_node_partial() operation that modify PG_workingset so all
the operations have to be atomic now.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index bcb5b2c4e213..f2cdb81ab02e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -522,7 +522,7 @@ static __always_inline void slab_unlock(struct slab *slab)
struct page *page = slab_page(slab);
VM_BUG_ON_PAGE(PageTail(page), page);
- __bit_spin_unlock(PG_locked, &page->flags);
+ bit_spin_unlock(PG_locked, &page->flags);
}
static inline bool
@@ -2127,12 +2127,12 @@ static inline bool slab_test_node_partial(const struct slab *slab)
static inline void slab_set_node_partial(struct slab *slab)
{
- __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+ set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
static inline void slab_clear_node_partial(struct slab *slab)
{
- __clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+ clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
/*
--
2.42.1
