From d77a117e6871ff78a06def46583d23752593de60 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 9 Mar 2016 14:08:10 -0800 Subject: 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 Reported-by: Eryu Guan Tested-by: Eryu Guan Cc: Ross Zwisler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/list_debug.c | 9 --------- 1 file changed, 9 deletions(-) (limited to 'lib/list_debug.c') diff --git a/lib/list_debug.c b/lib/list_debug.c index 3345a08..3859bf6 100644 --- a/lib/list_debug.c +++ b/lib/list_debug.c @@ -12,13 +12,6 @@ #include #include -static struct list_head force_poison; -void list_force_poison(struct list_head *entry) -{ - entry->next = &force_poison; - entry->prev = &force_poison; -} - /* * Insert a new entry between two known consecutive entries. * @@ -30,8 +23,6 @@ void __list_add(struct list_head *new, struct list_head *prev, struct list_head *next) { - WARN(new->next == &force_poison || new->prev == &force_poison, - "list_add attempted on force-poisoned entry\n"); WARN(next->prev != prev, "list_add corruption. next->prev should be " "prev (%p), but was %p. (next=%p).\n", -- cgit v1.1