From: Oscar Salvador <osalvador@suse.de>
To: Jane Chu <jane.chu@oracle.com>
Cc: linmiaohe@huawei.com, nao.horiguchi@gmail.com,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/5] mm/memory-failure: send SIGBUS in the event of thp split fail
Date: Thu, 16 May 2024 14:47:01 +0200 [thread overview]
Message-ID: <ZkYARVW2cOZcsFYB@localhost.localdomain> (raw)
In-Reply-To: <20240510062602.901510-6-jane.chu@oracle.com>
On Fri, May 10, 2024 at 12:26:02AM -0600, Jane Chu wrote:
> When handle hwpoison in a RDMA longterm pinned thp page,
> try_to_split_thp_page() will fail. And at this point, there is
> little else the kernel could do except sending a SIGBUS to
> the user process, thus give it a chance to recover.
Well, it does need to be a RDMA longterm pinned, right?
Anything holding an extra refcount can already make us bite the dust, so
I would not make it that specific.
> Signed-off-by: Jane Chu <jane.chu@oracle.com>
> ---
> mm/memory-failure.c | 31 ++++++++++++++++++++++++++-----
> 1 file changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2fa884d8b5a3..15bb1c0c42e8 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1697,7 +1697,7 @@ static int identify_page_state(unsigned long pfn, struct page *p,
> return page_action(ps, p, pfn);
> }
>
> -static int try_to_split_thp_page(struct page *page)
> +static int try_to_split_thp_page(struct page *page, bool release)
> {
> int ret;
>
> @@ -1705,7 +1705,7 @@ static int try_to_split_thp_page(struct page *page)
> ret = split_huge_page(page);
> unlock_page(page);
>
> - if (unlikely(ret))
> + if (ret && release)
> put_page(page);
I would document whhen and when not we can release the page.
E.g: we cannot release it if there are still processes mapping the thp.
> +static int kill_procs_now(struct page *p, unsigned long pfn, int flags,
> + struct folio *folio)
> +{
> + LIST_HEAD(tokill);
> +
> + collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);
> + kill_procs(&tokill, true, pfn, flags);
> +
> + return -EHWPOISON;
You are returning -EHWPOISON here,
> +}
> +
> /**
> * memory_failure - Handle memory failure of a page.
> * @pfn: Page Number of the corrupted page
> @@ -2313,8 +2331,11 @@ int memory_failure(unsigned long pfn, int flags)
> * page is a valid handlable page.
> */
> folio_set_has_hwpoisoned(folio);
> - if (try_to_split_thp_page(p) < 0) {
> - res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
> + if (try_to_split_thp_page(p, false) < 0) {
> + pr_err("%#lx: thp split failed\n", pfn);
> + res = kill_procs_now(p, pfn, flags, folio);
> + put_page(p);
> + res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_FAILED);
just to overwrite it here with action_result(). Which one do we need?
I think we would need -EBUSY here, right? So I would drop the retcode
from kill_procs_now.
Also, do we want the extra pr_err() here.
action_result() will already provide us the pfn and the
action_page_types which will be "unsplit thp". Is not that clear enough?
I would drop that.
--
Oscar Salvador
SUSE Labs
next prev parent reply other threads:[~2024-05-16 12:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 6:25 [PATCH v2 0/5] Enhance soft hwpoison handling and injection Jane Chu
2024-05-10 6:25 ` [PATCH v2 1/5] mm/memory-failure: try to send SIGBUS even if unmap failed Jane Chu
2024-05-11 7:01 ` Miaohe Lin
2024-05-10 6:25 ` [PATCH v2 2/5] mm/madvise: Add MF_ACTION_REQUIRED to madvise(MADV_HWPOISON) Jane Chu
2024-05-15 11:44 ` Oscar Salvador
2024-05-10 6:26 ` [PATCH v2 3/5] mm/memory-failure: improve memory failure action_result messages Jane Chu
2024-05-16 9:46 ` Oscar Salvador
2024-05-20 18:30 ` Jane Chu
2024-05-10 6:26 ` [PATCH v2 4/5] mm/memory-failure: move hwpoison_filter() higher up Jane Chu
2024-05-11 8:29 ` Miaohe Lin
2024-05-20 18:15 ` Jane Chu
2024-05-16 10:11 ` Oscar Salvador
2024-05-10 6:26 ` [PATCH v2 5/5] mm/memory-failure: send SIGBUS in the event of thp split fail Jane Chu
2024-05-16 12:47 ` Oscar Salvador [this message]
2024-05-20 18:48 ` Jane Chu
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