From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Oscar Salvador <osalvador@suse.de>,
Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
Steven Price <steven.price@arm.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Aili Yao <yaoaili@kingsoft.com>, Jiri Bohac <jbohac@suse.cz>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
linux-hyperv@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 6/6] fs/proc/kcore: use page_offline_(freeze|thaw)
Date: Mon, 17 May 2021 09:44:21 +0300 [thread overview]
Message-ID: <YKIQxXpp6AFGRUQ5@kernel.org> (raw)
In-Reply-To: <20210514172247.176750-7-david@redhat.com>
On Fri, May 14, 2021 at 07:22:47PM +0200, David Hildenbrand wrote:
> Let's properly synchronize with drivers that set PageOffline().
> Unfreeze/thaw every now and then, so drivers that want to set PageOffline()
> can make progress.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
> fs/proc/kcore.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index 92ff1e4436cb..982e694aae77 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -313,6 +313,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> {
> char *buf = file->private_data;
> size_t phdrs_offset, notes_offset, data_offset;
> + size_t page_offline_frozen = 1;
> size_t phdrs_len, notes_len;
> struct kcore_list *m;
> size_t tsz;
> @@ -322,6 +323,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> int ret = 0;
>
> down_read(&kclist_lock);
> + /*
> + * Don't race against drivers that set PageOffline() and expect no
> + * further page access.
> + */
> + page_offline_freeze();
>
> get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset);
> phdrs_offset = sizeof(struct elfhdr);
> @@ -480,6 +486,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> }
> }
>
> + if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
> + page_offline_thaw();
> + cond_resched();
> + page_offline_freeze();
> + }
> +
> if (&m->list == &kclist_head) {
> if (clear_user(buffer, tsz)) {
> ret = -EFAULT;
> @@ -565,6 +577,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> }
>
> out:
> + page_offline_thaw();
> up_read(&kclist_lock);
> if (ret)
> return ret;
> --
> 2.31.1
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2021-05-17 6:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 17:22 [PATCH v2 0/6] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages David Hildenbrand
2021-05-14 17:22 ` [PATCH v2 1/6] fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER David Hildenbrand
2021-05-14 17:22 ` [PATCH v2 2/6] fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM David Hildenbrand
2021-05-14 17:22 ` [PATCH v2 3/6] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages David Hildenbrand
2021-05-25 8:09 ` Oscar Salvador
2021-05-14 17:22 ` [PATCH v2 4/6] mm: introduce page_offline_(begin|end|freeze|thaw) to synchronize setting PageOffline() David Hildenbrand
2021-05-17 6:43 ` Mike Rapoport
2021-05-17 15:18 ` David Hildenbrand
2021-05-25 8:16 ` Oscar Salvador
2021-05-14 17:22 ` [PATCH v2 5/6] virtio-mem: use page_offline_(start|end) when " David Hildenbrand
2021-05-17 6:43 ` Mike Rapoport
2021-05-25 8:20 ` Oscar Salvador
2021-05-14 17:22 ` [PATCH v2 6/6] fs/proc/kcore: use page_offline_(freeze|thaw) David Hildenbrand
2021-05-17 6:44 ` Mike Rapoport [this message]
2021-05-25 8:21 ` Oscar Salvador
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