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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nfs.h
/*
* Copyright (c) 2012 Netapp, Inc. All rights reserved.
*
* Function and structures exported by the NFS module
* for use by NFS version-specific modules.
*/
#ifndef __LINUX_INTERNAL_NFS_H
#define __LINUX_INTERNAL_NFS_H
#include <linux/fs.h>
#include <linux/sunrpc/sched.h>
#include <linux/nfs_xdr.h>
struct nfs_subversion {
struct module *owner; /* THIS_MODULE pointer */
struct file_system_type *nfs_fs; /* NFS filesystem type */
const struct rpc_version *rpc_vers; /* NFS version information */
const struct nfs_rpc_ops *rpc_ops; /* NFS operations */
const struct super_operations *sops; /* NFS Super operations */
const struct xattr_handler **xattr; /* NFS xattr handlers */
struct list_head list; /* List of NFS versions */
};
struct nfs_subversion *get_nfs_version(unsigned int);
void put_nfs_version(struct nfs_subversion *);
void register_nfs_version(struct nfs_subversion *);
void unregister_nfs_version(struct nfs_subversion *);
#endif /* __LINUX_INTERNAL_NFS_H */
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