On 10/12/23 17:12, Mike Kravetz wrote:
> On 10/12/23 07:53, Mike Kravetz wrote:
> > On 10/11/23 17:03, Nathan Chancellor wrote:
> > > On Mon, Oct 09, 2023 at 06:23:45PM -0700, Mike Kravetz wrote:
> > > > On 10/09/23 15:56, Usama Arif wrote:
> >
> > Thank you Nathan! That is very helpful.
> >
> > I will use this information to try and recreate. If I can recreate, I
> > should be able to get to root cause.
>
> I could easily recreate the issue using the provided instructions. First
> thing I did was add a few printk's to check/verify state. The beginning
> of gather_bootmem_prealloc looked like this:
Hi Nathan,
This is looking more and more like a Clang issue to me. I did a little
more problem isolation today. Here is what I did:
- Check out commit "hugetlb: restructure pool allocations" in linux-next
- Fix the known issue with early disable/enable IRQs via locking by
applying:
commit 266789498210dff6cf9a14b64fa3a5cb2fcc5858
Author: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Date: Fri Oct 13 13:14:15 2023 -0700
fix prep_and_add_allocated_folios locking
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c843506654f8..d8ab2d9b391b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2246,15 +2246,16 @@ static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h,
static void prep_and_add_allocated_folios(struct hstate *h,
struct list_head *folio_list)
{
+ unsigned long flags;
struct folio *folio, *tmp_f;
/* Add all new pool pages to free lists in one lock cycle */
- spin_lock_irq(&hugetlb_lock);
+ spin_lock_irqsave(&hugetlb_lock, flags);
list_for_each_entry_safe(folio, tmp_f, folio_list, lru) {
__prep_account_new_huge_page(h, folio_nid(folio));
enqueue_hugetlb_folio(h, folio);
}
- spin_unlock_irq(&hugetlb_lock);
+ spin_unlock_irqrestore(&hugetlb_lock, flags);
}
/*
- Add the following code which would only trigger a BUG if we were to
traverse an empty list; which should NEVER happen.
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d8ab2d9b391b..be234831b33f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3294,11 +3294,21 @@ static void __init gather_bootmem_prealloc(void)
LIST_HEAD(folio_list);
struct huge_bootmem_page *m;
struct hstate *h, *prev_h = NULL;
+ bool empty;
+
+ empty = list_empty(&huge_boot_pages);
+ if (empty)
+ printk("gather_bootmem_prealloc: huge_boot_pages list empty\n");
list_for_each_entry(m, &huge_boot_pages, list) {
struct page *page = virt_to_page(m);
struct folio *folio = (void *)page;
+ if (empty) {
+ printk(" Traversing an empty list as if not empty!!!\n");
+ BUG();
+ }
+
h = m->hstate;
/*
* It is possible to have multiple huge page sizes (hstates)
- As you have experienced, this will BUG if built with LLVM 17.0.2 and
CONFIG_INIT_STACK_NONE
- It will NOT BUG if built with LLVM 13.0.1 but will BUG if built with
LLVM llvm-14.0.6-x86_64 and later.
As mentioned in the previous email, the generated code for loop entry
looks wrong to my untrained eyes. Can you or someone on the llvm team
take a look?
--
Mike Kravetz
