Revision 9a291a7c9428155e8e623e4a3989f8be47134df5 authored by James Morse on 02 June 2017, 21:46:46 UTC, committed by Linus Torvalds on 02 June 2017, 22:07:38 UTC
KVM uses get_user_pages() to resolve its stage2 faults. KVM sets the FOLL_HWPOISON flag causing faultin_page() to return -EHWPOISON when it finds a VM_FAULT_HWPOISON. KVM handles these hwpoison pages as a special case. (check_user_page_hwpoison()) When huge pages are involved, this doesn't work so well. get_user_pages() calls follow_hugetlb_page(), which stops early if it receives VM_FAULT_HWPOISON from hugetlb_fault(), eventually returning -EFAULT to the caller. The step to map this to -EHWPOISON based on the FOLL_ flags is missing. The hwpoison special case is skipped, and -EFAULT is returned to user-space, causing Qemu or kvmtool to exit. Instead, move this VM_FAULT_ to errno mapping code into a header file and use it from faultin_page() and follow_hugetlb_page(). With this, KVM works as expected. This isn't a problem for arm64 today as we haven't enabled MEMORY_FAILURE, but I can't see any reason this doesn't happen on x86 too, so I think this should be a fix. This doesn't apply earlier than stable's v4.11.1 due to all sorts of cleanup. [james.morse@arm.com: add vm_fault_to_errno() call to faultin_page()] suggested. Link: http://lkml.kernel.org/r/20170525171035.16359-1-james.morse@arm.com [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170524160900.28786-1-james.morse@arm.com Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Punit Agrawal <punit.agrawal@arm.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [4.11.1+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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nfs4idmap.h
/*
* fs/nfs/nfs4idmap.h
*
* UID and GID to name mapping for clients.
*
* Copyright (c) 2002 The Regents of the University of Michigan.
* All rights reserved.
*
* Marius Aamodt Eriksen <marius@umich.edu>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef NFS_IDMAP_H
#define NFS_IDMAP_H
#include <linux/uidgid.h>
#include <uapi/linux/nfs_idmap.h>
/* Forward declaration to make this header independent of others */
struct nfs_client;
struct nfs_server;
struct nfs_fattr;
struct nfs4_string;
int nfs_idmap_init(void);
void nfs_idmap_quit(void);
int nfs_idmap_new(struct nfs_client *);
void nfs_idmap_delete(struct nfs_client *);
void nfs_fattr_init_names(struct nfs_fattr *fattr,
struct nfs4_string *owner_name,
struct nfs4_string *group_name);
void nfs_fattr_free_names(struct nfs_fattr *);
void nfs_fattr_map_and_free_names(struct nfs_server *, struct nfs_fattr *);
int nfs_map_name_to_uid(const struct nfs_server *, const char *, size_t, kuid_t *);
int nfs_map_group_to_gid(const struct nfs_server *, const char *, size_t, kgid_t *);
int nfs_map_uid_to_name(const struct nfs_server *, kuid_t, char *, size_t);
int nfs_map_gid_to_group(const struct nfs_server *, kgid_t, char *, size_t);
int nfs_map_string_to_numeric(const char *name, size_t namelen, __u32 *res);
extern unsigned int nfs_idmap_cache_timeout;
#endif /* NFS_IDMAP_H */
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