Re: [PATCH 1/3] HWPOISON: fix action_result() to print out dirty/clean

Fengguang Wu
2012-08-23T09:33:36Z

On Wed, Aug 22, 2012 at 11:17:33AM -0400, Naoya Horiguchi wrote:
> action_result() fails to print out "dirty" even if an error occurred on a
> dirty pagecache, because when we check PageDirty in action_result() it was
> cleared after page isolation even if it's dirty before error handling. This
> can break some applications that monitor this message, so should be fixed.
>
> There are several callers of action_result() except page_action(), but
> either of them are not for LRU pages but for free pages or kernel pages,
> so we don't have to consider dirty or not for them.
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> ---
> mm/memory-failure.c | 22 +++++++++-------------
> 1 file changed, 9 insertions(+), 13 deletions(-)
>
> diff --git v3.6-rc1.orig/mm/memory-failure.c v3.6-rc1/mm/memory-failure.c
> index a6e2141..79dfb2f 100644
> --- v3.6-rc1.orig/mm/memory-failure.c
> +++ v3.6-rc1/mm/memory-failure.c
> @@ -779,16 +779,16 @@ static struct page_state {
> { compound, compound, "huge", me_huge_page },
> #endif
>
> - { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty },
> - { sc|dirty, sc, "swapcache", me_swapcache_clean },
> + { sc|dirty, sc|dirty, "dirty swapcache", me_swapcache_dirty },
> + { sc|dirty, sc, "clean swapcache", me_swapcache_clean },
>
> - { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
> - { unevict, unevict, "unevictable LRU", me_pagecache_clean},
> + { unevict|dirty, unevict|dirty, "dirty unevictable LRU", me_pagecache_dirty },
> + { unevict, unevict, "clean unevictable LRU", me_pagecache_clean },
>
> - { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
> - { mlock, mlock, "mlocked LRU", me_pagecache_clean },
> + { mlock|dirty, mlock|dirty, "dirty mlocked LRU", me_pagecache_dirty },
> + { mlock, mlock, "clean mlocked LRU", me_pagecache_clean },
>
> - { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
> + { lru|dirty, lru|dirty, "dirty LRU", me_pagecache_dirty },
> { lru|dirty, lru, "clean LRU", me_pagecache_clean },

According to the set_page_dirty() comment, the dirty bit might be set
outside the page lock (however I don't know any concrete examples).
That means the word "clean" is not 100% right. That's probably why we
only report "dirty LRU" and didn't say "clean LRU".

Thanks,
Fengguang

> /*
> @@ -812,12 +812,8 @@ static struct page_state {
>
> static void action_result(unsigned long pfn, char *msg, int result)
> {
> - struct page *page = pfn_to_page(pfn);
> -
> - printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
> - pfn,
> - PageDirty(page) ? "dirty " : "",
> - msg, action_name[result]);
> + pr_err("MCE %#lx: %s page recovery: %s\n",
> + pfn, msg, action_name[result]);
> }
>
> static int page_action(struct page_state *ps, struct page *p,
> --
> 1.7.11.4