From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org, "Jan Kara" <jack@suse.cz>,
"Christoph Hellwig" <hch@lst.de>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Matthew Wilcox" <mawilcox@microsoft.com>,
"Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>,
"Ross Zwisler" <ross.zwisler@linux.intel.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v4 11/12] mm, memory_failure: Teach memory_failure() about dev_pagemap pages
Date: Tue, 12 Jun 2018 14:14:20 -0600 [thread overview]
Message-ID: <20180612201420.GA12706@linux.intel.com> (raw)
In-Reply-To: <152850187949.38390.1012249765651998342.stgit@dwillia2-desk3.amr.corp.intel.com>
On Fri, Jun 08, 2018 at 04:51:19PM -0700, Dan Williams wrote:
> mce: Uncorrected hardware memory error in user-access at af34214200
> {1}[Hardware Error]: It has been corrected by h/w and requires no further action
> mce: [Hardware Error]: Machine check events logged
> {1}[Hardware Error]: event severity: corrected
> Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users
> [..]
> Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed
> mce: Memory error not recovered
>
> In contrast to typical memory, dev_pagemap pages may be dax mapped. With
> dax there is no possibility to map in another page dynamically since dax
> establishes 1:1 physical address to file offset associations. Also
> dev_pagemap pages associated with NVDIMM / persistent memory devices can
> internal remap/repair addresses with poison. While memory_failure()
> assumes that it can discard typical poisoned pages and keep them
> unmapped indefinitely, dev_pagemap pages may be returned to service
> after the error is cleared.
>
> Teach memory_failure() to detect and handle MEMORY_DEVICE_HOST
> dev_pagemap pages that have poison consumed by userspace. Mark the
> memory as UC instead of unmapping it completely to allow ongoing access
> via the device driver (nd_pmem). Later, nd_pmem will grow support for
> marking the page back to WB when the error is cleared.
>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: J�r�me Glisse <jglisse@redhat.com>
> Cc: Matthew Wilcox <mawilcox@microsoft.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
<>
> +static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
> + struct dev_pagemap *pgmap)
> +{
> + const bool unmap_success = true;
> + unsigned long size;
> + struct page *page;
> + LIST_HEAD(tokill);
> + int rc = -EBUSY;
> + loff_t start;
> +
> + /*
> + * Prevent the inode from being freed while we are interrogating
> + * the address_space, typically this would be handled by
> + * lock_page(), but dax pages do not use the page lock.
> + */
> + page = dax_lock_page(pfn);
> + if (!page)
> + goto out;
> +
> + if (hwpoison_filter(page)) {
> + rc = 0;
> + goto unlock;
> + }
> +
> + switch (pgmap->type) {
> + case MEMORY_DEVICE_PRIVATE:
> + case MEMORY_DEVICE_PUBLIC:
> + /*
> + * TODO: Handle HMM pages which may need coordination
> + * with device-side memory.
> + */
> + goto unlock;
> + default:
> + break;
> + }
> +
> + /*
> + * If the page is not mapped in userspace then report it as
> + * unhandled.
> + */
> + size = dax_mapping_size(page);
> + if (!size) {
> + pr_err("Memory failure: %#lx: failed to unmap page\n", pfn);
> + goto unlock;
> + }
> +
> + SetPageHWPoison(page);
> +
> + /*
> + * Unlike System-RAM there is no possibility to swap in a
> + * different physical page at a given virtual address, so all
> + * userspace consumption of ZONE_DEVICE memory necessitates
> + * SIGBUS (i.e. MF_MUST_KILL)
> + */
> + flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
> + collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
You know "flags & MF_ACTION_REQUIRED" will always be true, so you can just
pass in MF_ACTION_REQUIRED or even just "true".
> +
> + start = (page->index << PAGE_SHIFT) & ~(size - 1);
> + unmap_mapping_range(page->mapping, start, start + size, 0);
> +
> + kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, ilog2(size),
You know "flags & MF_MUST_KILL" will always be true, so you can just pass in
MF_MUST_KILL or even just "true".
Also, you can get rid of the constant "unmap_success" if you want and just
pass in false as the 3rd argument.
next prev parent reply other threads:[~2018-06-12 20:14 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-08 23:50 [PATCH v4 00/12] mm: Teach memory_failure() about ZONE_DEVICE pages Dan Williams
2018-06-08 23:50 ` [PATCH v4 01/12] device-dax: Convert to vmf_insert_mixed and vm_fault_t Dan Williams
2018-06-08 23:50 ` [PATCH v4 02/12] device-dax: Cleanup vm_fault de-reference chains Dan Williams
2018-06-11 17:12 ` Laurent Dufour
2018-06-11 17:14 ` Dan Williams
2018-06-08 23:50 ` [PATCH v4 03/12] device-dax: Enable page_mapping() Dan Williams
2018-06-08 23:50 ` [PATCH v4 04/12] device-dax: Set page->index Dan Williams
2018-06-08 23:50 ` [PATCH v4 05/12] filesystem-dax: " Dan Williams
2018-06-08 23:50 ` [PATCH v4 06/12] mm, madvise_inject_error: Let memory_failure() optionally take a page reference Dan Williams
2018-06-08 23:50 ` [PATCH v4 07/12] x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses Dan Williams
2018-06-08 23:51 ` [PATCH v4 08/12] x86/memory_failure: Introduce {set, clear}_mce_nospec() Dan Williams
2018-06-08 23:51 ` [PATCH v4 09/12] mm, memory_failure: Pass page size to kill_proc() Dan Williams
2018-06-08 23:51 ` [PATCH v4 10/12] filesystem-dax: Introduce dax_lock_page() Dan Williams
2018-06-11 15:41 ` Jan Kara
2018-06-11 16:48 ` Dan Williams
2018-06-12 18:07 ` Ross Zwisler
2018-07-04 15:20 ` Dan Williams
2018-07-04 15:17 ` Dan Williams
2018-06-12 18:15 ` Ross Zwisler
2018-07-04 15:11 ` Dan Williams
2018-06-08 23:51 ` [PATCH v4 11/12] mm, memory_failure: Teach memory_failure() about dev_pagemap pages Dan Williams
2018-06-11 15:50 ` Jan Kara
2018-06-11 16:45 ` Dan Williams
2018-06-12 20:14 ` Ross Zwisler [this message]
2018-06-12 23:38 ` Dan Williams
2018-06-08 23:51 ` [PATCH v4 12/12] libnvdimm, pmem: Restore page attributes when clearing errors Dan Williams
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