Re: [PATCH v7 0/2] rcu: Dump memory object info if callback function is invalid

[Paul E. McKenney]

On Sat, Aug 05, 2023 at 11:17:24AM +0800, thunder.leizhen@xxxxxxxxxxxxxxx wrote:
> From: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> 
> v6 --> v7:
> To avoid snowballing, resend the two RCU-related patches that we've discussed
> OK. The remaining three patches themselves do not need to be gone into RCU tree,
> I'll send them separately for discussion.
> 
> v5 --> v6:
> 1. Use print_hex_dump() to dump the memory of slab object.
> 2. Add a new dump prefix DUMP_PREFIX_ADDRESS_LOW16
> 3. Minimize the output width of the offset
> 
> v4 --> v5:
> 1. Add Reviewed-by Acked-by for patch 1/3
> 2. Add patch 3/3:
>    mm: Dump the memory of slab object in kmem_dump_obj()
> 
> v3 --> v4:
> 1. Remove kmem_valid_obj() and convert kmem_dump_obj() to work the same way
>    as vmalloc_dump_obj().
> 2. In kernel/rcu/rcu.h
> -#include <linux/mm.h>
> +#include <linux/slab.h>
> 
> v2 --> v3:
> 1. I made statistics about the source of 'rhp'. kmem_valid_obj() accounts for
>    more than 97.5%, and vmalloc accounts for less than 1%. So change call
>    mem_dump_obj() to call kmem_dump_obj() can meet debugging requirements and
>    avoid the potential deadlock risk of vmalloc_dump_obj().
> -		mem_dump_obj(rhp);
> +		if (kmem_valid_obj(rhp))
> +			kmem_dump_obj(rhp);
> 
>    The discussion about vmap_area_lock deadlock in v2:
>    https://lkml.org/lkml/2022/11/11/493
> 
> 2. Provide static inline empty functions for kmem_valid_obj() and kmem_dump_obj()
>    when CONFIG_PRINTK=n.
> 
> v1 --> v2:
> 1. Remove condition "(unsigned long)rhp->func & 0x3", it have problems on x86.
> 2. Paul E. McKenney helped me update the commit message, thanks.
> 
> 
> Zhen Lei (2):
>   mm: Remove kmem_valid_obj()
>   rcu: Dump memory object info if callback function is invalid

Queued both on -rcu, thank you all!

							Thanx, Paul

>  include/linux/slab.h  |  5 +++--
>  kernel/rcu/rcu.h      |  7 +++++++
>  kernel/rcu/srcutiny.c |  1 +
>  kernel/rcu/srcutree.c |  1 +
>  kernel/rcu/tasks.h    |  1 +
>  kernel/rcu/tiny.c     |  1 +
>  kernel/rcu/tree.c     |  1 +
>  mm/slab_common.c      | 41 +++++++++++------------------------------
>  mm/util.c             |  4 +---
>  9 files changed, 27 insertions(+), 35 deletions(-)
> 
> -- 
> 2.34.1
>