From: David Hildenbrand <david@redhat.com> To: Dave Young <dyoung@redhat.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devel@linuxdriverproject.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org, kexec-ml <kexec@lists.infradead.org>, pv-drivers@vmware.com, Andrew Morton <akpm@linux-foundation.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Baoquan He <bhe@redhat.com>, Omar Sandoval <osandov@fb.com>, Arnd Bergmann <arnd@arndb.de>, Matthew Wilcox <willy@infradead.org>, Michal Hocko <mhocko@suse.com>, "Michael S. Tsirkin" <mst@redhat.com>, Lianbo Jiang <lijiang@redhat.com>, Borislav Petkov <bp@alien8.de>, Kazuhito Hagio <k-hagio@ab.jp.nec.com> Subject: Re: [PATCH v2 3/8] kexec: export PG_offline to VMCOREINFO Date: Mon, 11 Mar 2019 10:55:41 +0100 [thread overview] Message-ID: <d9e578c3-5ae6-5e82-a0a8-14c7e12c729f@redhat.com> (raw) In-Reply-To: <20190311090402.GA12071@dhcp-128-65.nay.redhat.com> On 11.03.19 10:04, Dave Young wrote: > Hi David, > On 11/22/18 at 11:06am, David Hildenbrand wrote: >> Right now, pages inflated as part of a balloon driver will be dumped >> by dump tools like makedumpfile. While XEN is able to check in the >> crash kernel whether a certain pfn is actuall backed by memory in the >> hypervisor (see xen_oldmem_pfn_is_ram) and optimize this case, dumps of >> other balloon inflated memory will essentially result in zero pages getting >> allocated by the hypervisor and the dump getting filled with this data. >> >> The allocation and reading of zero pages can directly be avoided if a >> dumping tool could know which pages only contain stale information not to >> be dumped. >> >> We now have PG_offline which can be (and already is by virtio-balloon) >> used for marking pages as logically offline. Follow up patches will >> make use of this flag also in other balloon implementations. >> >> Let's export PG_offline via PAGE_OFFLINE_MAPCOUNT_VALUE, so >> makedumpfile can directly skip pages that are logically offline and the >> content therefore stale. (we export is as a macro to match how it is >> done for PG_buddy. This way it is clearer that this is not actually a flag >> but only a very specific mapcount value to represent page types). >> >> Please note that this is also helpful for a problem we were seeing under >> Hyper-V: Dumping logically offline memory (pages kept fake offline while >> onlining a section via online_page_callback) would under some condicions >> result in a kernel panic when dumping them. >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Dave Young <dyoung@redhat.com> >> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> >> Cc: Baoquan He <bhe@redhat.com> >> Cc: Omar Sandoval <osandov@fb.com> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Michal Hocko <mhocko@suse.com> >> Cc: "Michael S. Tsirkin" <mst@redhat.com> >> Cc: Lianbo Jiang <lijiang@redhat.com> >> Cc: Borislav Petkov <bp@alien8.de> >> Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com> >> Acked-by: Michael S. Tsirkin <mst@redhat.com> >> Acked-by: Dave Young <dyoung@redhat.com> >> Signed-off-by: David Hildenbrand <david@redhat.com> >> --- >> kernel/crash_core.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index 933cb3e45b98..093c9f917ed0 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -464,6 +464,8 @@ static int __init crash_save_vmcoreinfo_init(void) >> VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE); >> #ifdef CONFIG_HUGETLB_PAGE >> VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR); >> +#define PAGE_OFFLINE_MAPCOUNT_VALUE (~PG_offline) >> + VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE); >> #endif >> >> arch_crash_save_vmcoreinfo(); > > The patch has been merged, would you mind to send a documentation patch > for the vmcoreinfo, which is added recently in Documentation/kdump/vmcoreinfo.txt > > A brief description about how this vmcoreinfo field is used is good to > have. > Turns out, it was already documented PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision |PG_head_mask|PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy) |PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline) ----------------------------------------------------------------- Page attributes. These flags are used to filter various unnecessary for dumping pages. Thanks! > Thanks > Dave > -- Thanks, David / dhildenb
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com> To: Dave Young <dyoung@redhat.com> Cc: Michal Hocko <mhocko@suse.com>, Arnd Bergmann <arnd@arndb.de>, Baoquan He <bhe@redhat.com>, linux-pm@vger.kernel.org, pv-drivers@vmware.com, Borislav Petkov <bp@alien8.de>, linux-doc@vger.kernel.org, kexec-ml <kexec@lists.infradead.org>, linux-kernel@vger.kernel.org, Matthew Wilcox <willy@infradead.org>, linux-mm@kvack.org, Kazuhito Hagio <k-hagio@ab.jp.nec.com>, "Michael S. Tsirkin" <mst@redhat.com>, xen-devel@lists.xenproject.org, linux-fsdevel@vger.kernel.org, devel@linuxdriverproject.org, Andrew Morton <akpm@linux-foundation.org>, Omar Sandoval <osandov@fb.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Lianbo Jiang <lijiang@redhat.com> Subject: Re: [PATCH v2 3/8] kexec: export PG_offline to VMCOREINFO Date: Mon, 11 Mar 2019 10:55:41 +0100 [thread overview] Message-ID: <d9e578c3-5ae6-5e82-a0a8-14c7e12c729f@redhat.com> (raw) In-Reply-To: <20190311090402.GA12071@dhcp-128-65.nay.redhat.com> On 11.03.19 10:04, Dave Young wrote: > Hi David, > On 11/22/18 at 11:06am, David Hildenbrand wrote: >> Right now, pages inflated as part of a balloon driver will be dumped >> by dump tools like makedumpfile. While XEN is able to check in the >> crash kernel whether a certain pfn is actuall backed by memory in the >> hypervisor (see xen_oldmem_pfn_is_ram) and optimize this case, dumps of >> other balloon inflated memory will essentially result in zero pages getting >> allocated by the hypervisor and the dump getting filled with this data. >> >> The allocation and reading of zero pages can directly be avoided if a >> dumping tool could know which pages only contain stale information not to >> be dumped. >> >> We now have PG_offline which can be (and already is by virtio-balloon) >> used for marking pages as logically offline. Follow up patches will >> make use of this flag also in other balloon implementations. >> >> Let's export PG_offline via PAGE_OFFLINE_MAPCOUNT_VALUE, so >> makedumpfile can directly skip pages that are logically offline and the >> content therefore stale. (we export is as a macro to match how it is >> done for PG_buddy. This way it is clearer that this is not actually a flag >> but only a very specific mapcount value to represent page types). >> >> Please note that this is also helpful for a problem we were seeing under >> Hyper-V: Dumping logically offline memory (pages kept fake offline while >> onlining a section via online_page_callback) would under some condicions >> result in a kernel panic when dumping them. >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Dave Young <dyoung@redhat.com> >> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> >> Cc: Baoquan He <bhe@redhat.com> >> Cc: Omar Sandoval <osandov@fb.com> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Michal Hocko <mhocko@suse.com> >> Cc: "Michael S. Tsirkin" <mst@redhat.com> >> Cc: Lianbo Jiang <lijiang@redhat.com> >> Cc: Borislav Petkov <bp@alien8.de> >> Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com> >> Acked-by: Michael S. Tsirkin <mst@redhat.com> >> Acked-by: Dave Young <dyoung@redhat.com> >> Signed-off-by: David Hildenbrand <david@redhat.com> >> --- >> kernel/crash_core.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index 933cb3e45b98..093c9f917ed0 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -464,6 +464,8 @@ static int __init crash_save_vmcoreinfo_init(void) >> VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE); >> #ifdef CONFIG_HUGETLB_PAGE >> VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR); >> +#define PAGE_OFFLINE_MAPCOUNT_VALUE (~PG_offline) >> + VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE); >> #endif >> >> arch_crash_save_vmcoreinfo(); > > The patch has been merged, would you mind to send a documentation patch > for the vmcoreinfo, which is added recently in Documentation/kdump/vmcoreinfo.txt > > A brief description about how this vmcoreinfo field is used is good to > have. > Turns out, it was already documented PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision |PG_head_mask|PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy) |PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline) ----------------------------------------------------------------- Page attributes. These flags are used to filter various unnecessary for dumping pages. Thanks! > Thanks > Dave > -- Thanks, David / dhildenb _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2019-03-11 9:55 UTC|newest] Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-22 10:06 [PATCH v2 0/8] mm/kdump: allow to exclude pages that are logically offline David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 1/8] mm: balloon: update comment about isolation/migration/compaction David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 2/8] mm: convert PG_balloon to PG_offline David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 3/8] kexec: export PG_offline to VMCOREINFO David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2019-03-11 9:04 ` Dave Young 2019-03-11 9:04 ` Dave Young 2019-03-11 9:04 ` Dave Young 2019-03-11 9:55 ` David Hildenbrand 2019-03-11 9:55 ` David Hildenbrand [this message] 2019-03-11 9:55 ` David Hildenbrand 2019-03-11 10:04 ` Dave Young 2019-03-11 10:04 ` Dave Young 2019-03-11 10:04 ` Dave Young 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 4/8] xen/balloon: mark inflated pages PG_offline David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-23 13:41 ` Juergen Gross 2018-11-23 13:41 ` Juergen Gross 2018-11-23 13:41 ` Juergen Gross 2018-11-23 13:41 ` Juergen Gross 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 5/8] hv_balloon: " David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 6/8] vmw_balloon: " David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 7/8] PM / Hibernate: use pfn_to_online_page() David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` [PATCH v2 8/8] PM / Hibernate: exclude all PageOffline() pages David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:06 ` David Hildenbrand 2018-11-22 10:09 ` [PATCH v2] makedumpfile: exclude pages that are logically offline David Hildenbrand 2018-11-22 10:09 ` David Hildenbrand 2018-11-22 10:09 ` David Hildenbrand 2018-11-27 16:32 ` Kazuhito Hagio 2018-11-27 16:32 ` Kazuhito Hagio 2018-11-27 16:32 ` Kazuhito Hagio 2019-03-07 8:41 ` David Hildenbrand 2019-03-07 8:41 ` David Hildenbrand 2019-03-07 8:41 ` David Hildenbrand 2019-03-11 16:40 ` Kazuhito Hagio 2019-03-11 16:40 ` Kazuhito Hagio 2019-03-11 16:40 ` Kazuhito Hagio 2018-11-27 16:32 ` Kazuhito Hagio 2019-02-27 5:32 ` [PATCH v2 0/8] mm/kdump: allow to " Dave Young 2019-02-27 5:32 ` Dave Young 2019-02-27 5:32 ` Dave Young 2019-02-28 19:45 ` Andrew Morton 2019-02-28 19:45 ` Andrew Morton 2019-02-28 19:45 ` Andrew Morton 2019-02-28 19:45 ` Andrew Morton 2019-02-28 19:54 ` Boris Ostrovsky 2019-02-28 19:54 ` Boris Ostrovsky 2019-02-28 19:54 ` Boris Ostrovsky 2019-02-28 19:54 ` Boris Ostrovsky 2019-03-04 6:21 ` Dave Young 2019-03-04 6:21 ` Dave Young 2019-03-04 6:21 ` Dave Young 2019-03-04 6:21 ` Dave Young 2019-03-04 7:14 ` Juergen Gross [not found] ` <20190304062118.GA31037-0VdLhd/A9Pl+NNSt+8eSiB/sF2h8X+2i0E9HWUfgJXw@public.gmane.org> 2019-03-04 7:14 ` Juergen Gross 2019-03-04 7:14 ` Juergen Gross 2019-03-04 7:14 ` Juergen Gross 2019-02-27 5:32 ` Dave Young
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