Re: 2.6.25-git2: BUG: unable to handle kernel paging request at ffffffffffffffff

From: Paul E. McKenney
Date: Mon Apr 21 2008 - 01:47:46 EST


On Sun, Apr 20, 2008 at 09:59:11PM -0700, Paul E. McKenney wrote:
> And here is an update with one bug fixed -- testing continues.
> This is an update of http://lkml.org/lkml/2008/4/20/217, deleting
> list_for_each_safe_rcu() and fixing hlist_for_each_entry_rcu().
> Testing continues...

And it passes.

Thanx, Paul

> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---
>
> list.h | 48 +++++++++++++++---------------------------------
> 1 file changed, 15 insertions(+), 33 deletions(-)
>
> diff -urpNa -X dontdiff linux-2.6.25/include/linux/list.h linux-2.6.25-rcu-list/include/linux/list.h
> --- linux-2.6.25/include/linux/list.h 2008-04-16 19:49:44.000000000 -0700
> +++ linux-2.6.25-rcu-list/include/linux/list.h 2008-04-20 21:48:29.000000000 -0700
> @@ -631,31 +631,14 @@ static inline void list_splice_init_rcu(
> * as long as the traversal is guarded by rcu_read_lock().
> */
> #define list_for_each_rcu(pos, head) \
> - for (pos = (head)->next; \
> - prefetch(rcu_dereference(pos)->next), pos != (head); \
> - pos = pos->next)
> + for (pos = rcu_dereference((head)->next); \
> + prefetch(pos->next), pos != (head); \
> + pos = rcu_dereference(pos->next))
>
> #define __list_for_each_rcu(pos, head) \
> - for (pos = (head)->next; \
> - rcu_dereference(pos) != (head); \
> - pos = pos->next)
> -
> -/**
> - * list_for_each_safe_rcu
> - * @pos: the &struct list_head to use as a loop cursor.
> - * @n: another &struct list_head to use as temporary storage
> - * @head: the head for your list.
> - *
> - * Iterate over an rcu-protected list, safe against removal of list entry.
> - *
> - * This list-traversal primitive may safely run concurrently with
> - * the _rcu list-mutation primitives such as list_add_rcu()
> - * as long as the traversal is guarded by rcu_read_lock().
> - */
> -#define list_for_each_safe_rcu(pos, n, head) \
> - for (pos = (head)->next; \
> - n = rcu_dereference(pos)->next, pos != (head); \
> - pos = n)
> + for (pos = rcu_dereference((head)->next); \
> + pos != (head); \
> + pos = rcu_dereference(pos->next))
>
> /**
> * list_for_each_entry_rcu - iterate over rcu list of given type
> @@ -668,10 +651,9 @@ static inline void list_splice_init_rcu(
> * as long as the traversal is guarded by rcu_read_lock().
> */
> #define list_for_each_entry_rcu(pos, head, member) \
> - for (pos = list_entry((head)->next, typeof(*pos), member); \
> - prefetch(rcu_dereference(pos)->member.next), \
> - &pos->member != (head); \
> - pos = list_entry(pos->member.next, typeof(*pos), member))
> + for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \
> + prefetch(pos->member.next), &pos->member != (head); \
> + pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member))
>
>
> /**
> @@ -686,9 +668,9 @@ static inline void list_splice_init_rcu(
> * as long as the traversal is guarded by rcu_read_lock().
> */
> #define list_for_each_continue_rcu(pos, head) \
> - for ((pos) = (pos)->next; \
> - prefetch(rcu_dereference((pos))->next), (pos) != (head); \
> - (pos) = (pos)->next)
> + for ((pos) = rcu_dereference((pos)->next); \
> + prefetch((pos)->next), (pos) != (head); \
> + (pos) = rcu_dereference((pos)->next))
>
> /*
> * Double linked lists with a single pointer list head.
> @@ -986,10 +968,10 @@ static inline void hlist_add_after_rcu(s
> * as long as the traversal is guarded by rcu_read_lock().
> */
> #define hlist_for_each_entry_rcu(tpos, pos, head, member) \
> - for (pos = (head)->first; \
> - rcu_dereference(pos) && ({ prefetch(pos->next); 1;}) && \
> + for (pos = rcu_dereference((head)->first); \
> + pos && ({ prefetch(pos->next); 1;}) && \
> ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
> - pos = pos->next)
> + pos = rcu_dereference(pos->next))
>
> #else
> #warning "don't include kernel headers in userspace"
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