On 4/16/18 5:58 PM, Guenter Roeck wrote:
On Mon, Apr 16, 2018 at 02:43:01PM +0200, Vitaly Wool wrote:
Hey Guenter,
On 04/13/2018 07:56 PM, Guenter Roeck wrote:
On Fri, Apr 13, 2018 at 05:40:18PM +0000, Vitaly Wool wrote:
On Fri, Apr 13, 2018, 7:35 PM Guenter Roeck <li...@roeck-us.net> wrote:
On Fri, Apr 13, 2018 at 05:21:02AM +0000, Vitaly Wool wrote:
Hi Guenter,
Den fre 13 apr. 2018 kl 00:01 skrev Guenter Roeck <li...@roeck-us.net>:
Hi all,
we are observing crashes with z3pool under memory pressure. The kernel
version
used to reproduce the problem is v4.16-11827-g5d1365940a68, but the
problem was
also seen with v4.14 based kernels.
just before I dig into this, could you please try reproducing the errors
you see with https://patchwork.kernel.org/patch/10210459/ applied?
As mentioned above, I tested with v4.16-11827-g5d1365940a68, which already
includes this patch.
Bah. Sorry. Expect an update after the weekend.
NP; easy to miss. Thanks a lot for looking into it.
I wonder if the following patch would make a difference:
diff --git a/mm/z3fold.c b/mm/z3fold.c
index c0bca6153b95..5e547c2d5832 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -887,19 +887,21 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool,
unsigned int retries)
goto next;
}
next:
- spin_lock(&pool->lock);
if (test_bit(PAGE_HEADLESS, &page->private)) {
if (ret == 0) {
- spin_unlock(&pool->lock);
free_z3fold_page(page);
return 0;
}
- } else if (kref_put(&zhdr->refcount, release_z3fold_page)) {
- atomic64_dec(&pool->pages_nr);
- spin_unlock(&pool->lock);
- return 0;
+ } else {
+ spin_lock(&zhdr->page_lock);
+ if (kref_put(&zhdr->refcount,
release_z3fold_page_locked)) {
+ atomic64_dec(&pool->pages_nr);
+ return 0;
+ }
+ spin_unlock(&zhdr->page_lock);
}
+ spin_lock(&pool->lock);
/*
* Add to the beginning of LRU.
* Pool lock has to be kept here to ensure the page has
No, it doesn't. Same crash.
BUG: MAX_LOCK_DEPTH too low!
turning off the locking correctness validator.
depth: 48 max: 48!
48 locks held by kswapd0/51:
#0: 000000004d7a35a9 (&(&pool->lock)->rlock#3){+.+.}, at:
z3fold_zpool_shrink+0x47/0x3e0
#1: 000000007739f49e (&(&zhdr->page_lock)->rlock){+.+.}, at:
z3fold_zpool_shrink+0xb7/0x3e0
#2: 00000000ff6cd4c8 (&(&zhdr->page_lock)->rlock){+.+.}, at:
z3fold_zpool_shrink+0xb7/0x3e0
#3: 000000004cffc6cb (&(&zhdr->page_lock)->rlock){+.+.}, at:
z3fold_zpool_shrink+0xb7/0x3e0
...
PU: 0 PID: 51 Comm: kswapd0 Not tainted 4.17.0-rc1-yocto-standard+ #11
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1 04/01/2014
Call Trace:
dump_stack+0x67/0x9b
__lock_acquire+0x429/0x18f0
? __lock_acquire+0x2af/0x18f0
? __lock_acquire+0x2af/0x18f0
? lock_acquire+0x93/0x230
lock_acquire+0x93/0x230
? z3fold_zpool_shrink+0xb7/0x3e0
_raw_spin_trylock+0x65/0x80
? z3fold_zpool_shrink+0xb7/0x3e0
? z3fold_zpool_shrink+0x47/0x3e0
z3fold_zpool_shrink+0xb7/0x3e0
zswap_frontswap_store+0x180/0x7c0
...
BUG: sleeping function called from invalid context at mm/page_alloc.c:4320
in_atomic(): 1, irqs_disabled(): 0, pid: 51, name: kswapd0
INFO: lockdep is turned off.
Preemption disabled at:
[<0000000000000000>] (null)
CPU: 0 PID: 51 Comm: kswapd0 Not tainted 4.17.0-rc1-yocto-standard+ #11
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1 04/01/2014
Call Trace:
dump_stack+0x67/0x9b
___might_sleep+0x16c/0x250
__alloc_pages_nodemask+0x1e7/0x1490
? lock_acquire+0x93/0x230
? lock_acquire+0x93/0x230
__read_swap_cache_async+0x14d/0x260
zswap_writeback_entry+0xdb/0x340
z3fold_zpool_shrink+0x2b1/0x3e0
zswap_frontswap_store+0x180/0x7c0
? page_vma_mapped_walk+0x22/0x230
__frontswap_store+0x6e/0xf0
swap_writepage+0x49/0x70
...
This is with your patch applied on top of v4.17-rc1.
Guenter
Ugh. Could you please keep that patch and apply this on top:
diff --git a/mm/z3fold.c b/mm/z3fold.c
index c0bca6153b95..e8a80d044d9e 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -840,6 +840,7 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool,
unsigned int retries)
kref_get(&zhdr->refcount);
list_del_init(&zhdr->buddy);
zhdr->cpu = -1;
+ break;
}
list_del_init(&page->lru);
Thanks,
Vitaly
