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authorDan Williams <dan.j.williams@intel.com>2016-03-09 23:08:10 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-10 00:43:42 +0100
commitd77a117e6871ff78a06def46583d23752593de60 (patch)
tree79bf0536897d69bcca3832dd77f4ac1ce6ec034e /kernel/memremap.c
parentmm: __delete_from_page_cache show Bad page if mapped (diff)
downloadlinux-d77a117e6871ff78a06def46583d23752593de60.tar.xz
linux-d77a117e6871ff78a06def46583d23752593de60.zip
list: kill list_force_poison()
Given we have uninitialized list_heads being passed to list_add() it will always be the case that those uninitialized values randomly trigger the poison value. Especially since a list_add() operation will seed the stack with the poison value for later stack allocations to trip over. For example, see these two false positive reports: list_add attempted on force-poisoned entry WARNING: at lib/list_debug.c:34 [..] NIP [c00000000043c390] __list_add+0xb0/0x150 LR [c00000000043c38c] __list_add+0xac/0x150 Call Trace: __list_add+0xac/0x150 (unreliable) __down+0x4c/0xf8 down+0x68/0x70 xfs_buf_lock+0x4c/0x150 [xfs] list_add attempted on force-poisoned entry(0000000000000500), new->next == d0000000059ecdb0, new->prev == 0000000000000500 WARNING: at lib/list_debug.c:33 [..] NIP [c00000000042db78] __list_add+0xa8/0x140 LR [c00000000042db74] __list_add+0xa4/0x140 Call Trace: __list_add+0xa4/0x140 (unreliable) rwsem_down_read_failed+0x6c/0x1a0 down_read+0x58/0x60 xfs_log_commit_cil+0x7c/0x600 [xfs] Fixes: commit 5c2c2587b132 ("mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Eryu Guan <eguan@redhat.com> Tested-by: Eryu Guan <eguan@redhat.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/memremap.c')
-rw-r--r--kernel/memremap.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index b981a7b023f0..778191e3e887 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -351,8 +351,13 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
for_each_device_pfn(pfn, page_map) {
struct page *page = pfn_to_page(pfn);
- /* ZONE_DEVICE pages must never appear on a slab lru */
- list_force_poison(&page->lru);
+ /*
+ * ZONE_DEVICE pages union ->lru with a ->pgmap back
+ * pointer. It is a bug if a ZONE_DEVICE page is ever
+ * freed or placed on a driver-private list. Seed the
+ * storage with LIST_POISON* values.
+ */
+ list_del(&page->lru);
page->pgmap = pgmap;
}
devres_add(dev, page_map);