On 11/15/21 00:40, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
>
> Originally mf_mutex is introduced to serialize multiple MCE events, but
> it is not that useful to allow unpoison to run in parallel with memory_failure()
> and soft offline. So apply mf_mutex to soft offline and unpoison.
> The memory failure handler and soft offline handler get simpler with this.
>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
> ---
> ChangeLog v4:
> - fix type in commit description.
>
> ChangeLog v3:
> - merge with "mm/hwpoison: remove race consideration"
> - update description
>
> ChangeLog v2:
> - add mutex_unlock() in "page already poisoned" path in soft_offline_page().
> (Thanks to Ding Hui)
> ---
> mm/memory-failure.c | 62 +++++++++++++--------------------------------
> 1 file changed, 18 insertions(+), 44 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index e8c38e27b753..d29c79de6034 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
Thanks for working on this. I tried to exercise memory error handling for
hugetlb pages and ran into issues addressed by these patches.
> @@ -1507,14 +1507,6 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags)
> lock_page(head);
> page_flags = head->flags;
>
> - if (!PageHWPoison(head)) {
> - pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
> - num_poisoned_pages_dec();
> - unlock_page(head);
> - put_page(head);
> - return 0;
> - }
> -
> /*
> * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so
> * simply disable it. In order to make it work properly, we need
> @@ -1628,6 +1620,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
> return rc;
> }
>
> +static DEFINE_MUTEX(mf_mutex);
There are only two places other places where PageHWPoison is modified without
the mutex. They are:
- test_and_clear_pmem_poison
I 'think' pmem error handling is done separately so this does not apply.
- clear_hwpoisoned_pages
Called before removing memory (and deleting memmap) to reconcile count
of poisoned pages. Should not be an issue and technically I do not think
the ClearPageHWPoison() is actually needed in this routine.
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
--
Mike Kravetz
