From ca4810f2b6758489c9fb3e2365abf1ca6f367f5c Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Sat, 23 Jan 2021 21:01:52 -0800
Subject: [PATCH] mm: fix page reference leak in soft_offline_page()
References: git fixes (mm/memory-failure)
Patch-mainline: v5.11-rc5
Git-commit: dad4e5b390866ca902653df0daa864ae4b8d4147
The conversion to move pfn_to_online_page() internal to
soft_offline_page() missed that the get_user_pages() reference taken by
the madvise() path needs to be dropped when pfn_to_online_page() fails.
Note the direct sysfs-path to soft_offline_page() does not perform a
get_user_pages() lookup.
When soft_offline_page() is handed a pfn_valid() && !pfn_to_online_page()
pfn the kernel hangs at dax-device shutdown due to a leaked reference.
Link: https://lkml.kernel.org/r/161058501210.1840162.8108917599181157327.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/memory-failure.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ba254c94768f..c2e6703f6953 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1850,6 +1850,12 @@ static int soft_offline_free_page(struct page *page)
return rc;
}
+static void put_ref_page(struct page *page)
+{
+ if (page)
+ put_page(page);
+}
+
/**
* soft_offline_page - Soft offline a page.
* @pfn: pfn to soft-offline
@@ -1875,20 +1881,26 @@ static int soft_offline_free_page(struct page *page)
int soft_offline_page(unsigned long pfn, int flags)
{
int ret;
- struct page *page;
bool try_again = true;
+ struct page *page, *ref_page = NULL;
+
+ WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED));
if (!pfn_valid(pfn))
return -ENXIO;
+ if (flags & MF_COUNT_INCREASED)
+ ref_page = pfn_to_page(pfn);
+
/* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
page = pfn_to_online_page(pfn);
- if (!page)
+ if (!page) {
+ put_ref_page(ref_page);
return -EIO;
+ }
if (PageHWPoison(page)) {
pr_info("soft offline: %#lx page already poisoned\n", pfn);
- if (flags & MF_COUNT_INCREASED)
- put_page(page);
+ put_ref_page(ref_page);
return 0;
}