On 28 Apr 2022, at 8:33, Qian Cai wrote: > On Wed, Apr 27, 2022 at 05:04:39PM -0400, Zi Yan wrote: >> Do you mind checking if the patch below fixes the issue? It works >> for me. >> >> The original code was trying to migrate non-migratible compound pages >> (high-order slab pages from my tests) during isolation and caused >> an infinite loop. The patch avoids non-migratible pages. >> >> I will update my patch series once we confirm the patch fixes >> the bug. > > I am not able to apply it on today's linux-next tree. > > $ patch -Np1 --dry-run < ../patch/migrate.patch > checking file mm/page_isolation.c > Hunk #1 FAILED at 367. > 1 out of 1 hunk FAILED How about the one attached? I can apply it to next-20220428. Let me know if you are using a different branch. Thanks. -- Best Regards, Yan, Zi
From 1567f4dbc287f6fe2fa6d4dc63fa1f9137692cff Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@xxxxxxxxxx>
Date: Wed, 27 Apr 2022 16:49:22 -0400
Subject: [PATCH] fix what can be migrated what cannot.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
mm/page_isolation.c | 88 +++++++++++++++++++++++++--------------------
1 file changed, 49 insertions(+), 39 deletions(-)
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 75e454f5cf45..7968a1dd692a 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -367,58 +367,68 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, gfp_t gfp_flags,
}
/*
* migrate compound pages then let the free page handling code
- * above do the rest. If migration is not enabled, just fail.
+ * above do the rest. If migration is not possible, just fail.
*/
- if (PageHuge(page) || PageTransCompound(page)) {
-#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+ if (PageCompound(page)) {
unsigned long nr_pages = compound_nr(page);
- int order = compound_order(page);
struct page *head = compound_head(page);
unsigned long head_pfn = page_to_pfn(head);
- int ret;
- struct compact_control cc = {
- .nr_migratepages = 0,
- .order = -1,
- .zone = page_zone(pfn_to_page(head_pfn)),
- .mode = MIGRATE_SYNC,
- .ignore_skip_hint = true,
- .no_set_skip_hint = true,
- .gfp_mask = gfp_flags,
- .alloc_contig = true,
- };
- INIT_LIST_HEAD(&cc.migratepages);
if (head_pfn + nr_pages < boundary_pfn) {
- pfn += nr_pages;
+ pfn = head_pfn + nr_pages;
continue;
}
- ret = __alloc_contig_migrate_range(&cc, head_pfn,
- head_pfn + nr_pages);
-
- if (ret)
- goto failed;
+#if defined CONFIG_MIGRATION
/*
- * reset pfn, let the free page handling code above
- * split the free page to the right migratetype list.
- *
- * head_pfn is not used here as a hugetlb page order
- * can be bigger than MAX_ORDER-1, but after it is
- * freed, the free page order is not. Use pfn within
- * the range to find the head of the free page and
- * reset order to 0 if a hugetlb page with
- * >MAX_ORDER-1 order is encountered.
+ * hugetlb, lru compound (THP), and movable compound pages
+ * can be migrated. Otherwise, fail the isolation.
*/
- if (order > MAX_ORDER-1)
+ if (PageHuge(page) || PageLRU(page) || __PageMovable(page)) {
+ int order;
+ unsigned long outer_pfn;
+ int ret;
+ struct compact_control cc = {
+ .nr_migratepages = 0,
+ .order = -1,
+ .zone = page_zone(pfn_to_page(head_pfn)),
+ .mode = MIGRATE_SYNC,
+ .ignore_skip_hint = true,
+ .no_set_skip_hint = true,
+ .gfp_mask = gfp_flags,
+ .alloc_contig = true,
+ };
+ INIT_LIST_HEAD(&cc.migratepages);
+
+ ret = __alloc_contig_migrate_range(&cc, head_pfn,
+ head_pfn + nr_pages);
+
+ if (ret)
+ goto failed;
+ /*
+ * reset pfn to the head of the free page, so
+ * that the free page handling code above can split
+ * the free page to the right migratetype list.
+ *
+ * head_pfn is not used here as a hugetlb page order
+ * can be bigger than MAX_ORDER-1, but after it is
+ * freed, the free page order is not. Use pfn within
+ * the range to find the head of the free page.
+ */
order = 0;
- while (!PageBuddy(pfn_to_page(pfn))) {
- order++;
- pfn &= ~0UL << order;
- }
- continue;
-#else
- goto failed;
+ outer_pfn = pfn;
+ while (!PageBuddy(pfn_to_page(outer_pfn))) {
+ if (++order >= MAX_ORDER) {
+ outer_pfn = pfn;
+ break;
+ }
+ outer_pfn &= ~0UL << order;
+ }
+ pfn = outer_pfn;
+ continue;
+ } else
#endif
+ goto failed;
}
pfn++;
--
2.35.1
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