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Message-ID: <CAGWkznE0psiqZYSRjF+Joq73--Yo-xUhGD0gnBa42fYC55BFdA@mail.gmail.com>
Date: Wed, 22 May 2024 13:37:46 +0800
From: Zhaoyang Huang <huangzhaoyang@...il.com>
To: Marcin Wanat <private@...cinwanat.pl>
Cc: Dave Chinner <david@...morbit.com>, Andrew Morton <akpm@...ux-foundation.org>,
"zhaoyang.huang" <zhaoyang.huang@...soc.com>, Alex Shi <alexs@...nel.org>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Hugh Dickins <hughd@...gle.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, steve.kang@...soc.com
Subject: Re: [PATCH 1/1] mm: protect xa split stuff under lruvec->lru_lock
during migration
On Tue, May 21, 2024 at 11:47 PM Marcin Wanat <private@...cinwanat.pl> wrote:
>
> On 21.05.2024 03:00, Zhaoyang Huang wrote:
> > On Tue, May 21, 2024 at 8:58 AM Zhaoyang Huang <huangzhaoyang@...il.com> wrote:
> >>
> >> On Tue, May 21, 2024 at 3:42 AM Marcin Wanat <private@...cinwanat.pl> wrote:
> >>>
> >>> On 15.04.2024 03:50, Zhaoyang Huang wrote:
> >>> I have around 50 hosts handling high I/O (each with 20Gbps+ uplinks
> >>> and multiple NVMe drives), running RockyLinux 8/9. The stock RHEL
> >>> kernel 8/9 is NOT affected, and the long-term kernel 5.15.X is NOT affected.
> >>> However, with long-term kernels 6.1.XX and 6.6.XX,
> >>> (tested at least 10 different versions), this lockup always appears
> >>> after 2-30 days, similar to the report in the original thread.
> >>> The more load (for example, copying a lot of local files while
> >>> serving 20Gbps traffic), the higher the chance that the bug will appear.
> >>>
> >>> I haven't been able to reproduce this during synthetic tests,
> >>> but it always occurs in production on 6.1.X and 6.6.X within 2-30 days.
> >>> If anyone can provide a patch, I can test it on multiple machines
> >>> over the next few days.
> >> Could you please try this one which could be applied on 6.6 directly. Thank you!
> > URL: https://lore.kernel.org/linux-mm/20240412064353.133497-1-zhaoyang.huang@unisoc.com/
> >
>
> Unfortunately, I am unable to cleanly apply this patch against the
> latest 6.6.31
Please try below one which works on my v6.6 based android. Thank you
for your test in advance :D
mm/huge_memory.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 064fbd90822b..5899906c326a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2498,7 +2498,7 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
{
struct folio *folio = page_folio(page);
struct page *head = &folio->page;
- struct lruvec *lruvec;
+ struct lruvec *lruvec = folio_lruvec(folio);
struct address_space *swap_cache = NULL;
unsigned long offset = 0;
unsigned int nr = thp_nr_pages(head);
@@ -2513,9 +2513,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
xa_lock(&swap_cache->i_pages);
}
- /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
- lruvec = folio_lruvec_lock(folio);
-
ClearPageHasHWPoisoned(head);
for (i = nr - 1; i >= 1; i--) {
@@ -2541,9 +2538,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
}
ClearPageCompound(head);
- unlock_page_lruvec(lruvec);
- /* Caller disabled irqs, so they are still disabled here */
-
split_page_owner(head, nr);
/* See comment in __split_huge_page_tail() */
@@ -2560,7 +2554,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
page_ref_add(head, 2);
xa_unlock(&head->mapping->i_pages);
}
- local_irq_enable();
if (nr_dropped)
shmem_uncharge(head->mapping->host, nr_dropped);
@@ -2631,6 +2624,7 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)
int extra_pins, ret;
pgoff_t end;
bool is_hzp;
+ struct lruvec *lruvec;
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
@@ -2714,6 +2708,14 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)
/* block interrupt reentry in xa_lock and spinlock */
local_irq_disable();
+
+ /*
+ * take lruvec's lock before freeze the folio to prevent the folio
+ * remains in the page cache with refcnt == 0, which could lead to
+ * find_get_entry enters livelock by iterating the xarray.
+ */
+ lruvec = folio_lruvec_lock(folio);
+
if (mapping) {
/*
* Check if the folio is present in page cache.
@@ -2748,12 +2750,16 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)
}
__split_huge_page(page, list, end);
+ unlock_page_lruvec(lruvec);
+ local_irq_enable();
ret = 0;
} else {
spin_unlock(&ds_queue->split_queue_lock);
fail:
if (mapping)
xas_unlock(&xas);
+
+ unlock_page_lruvec(lruvec);
local_irq_enable();
remap_page(folio, folio_nr_pages(folio));
ret = -EAGAIN;
--
2.25.1
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