Revision b3ecba096729f521312d1863ad22530695527aed authored by Jeff Layton on 13 November 2014, 12:30:46 UTC, committed by Trond Myklebust on 13 November 2014, 18:15:49 UTC
Bruce reported that he was seeing the following BUG pop:
BUG: sleeping function called from invalid context at mm/slab.c:2846
in_atomic(): 0, irqs_disabled(): 0, pid: 4539, name: mount.nfs
2 locks held by mount.nfs/4539:
#0: (nfs_clid_init_mutex){+.+.+.}, at: [<ffffffffa01c0a9a>] nfs4_discover_server_trunking+0x4a/0x2f0 [nfsv4]
#1: (rcu_read_lock){......}, at: [<ffffffffa00e3185>] gss_stringify_acceptor+0x5/0xb0 [auth_rpcgss]
Preemption disabled at:[<ffffffff81a4f082>] printk+0x4d/0x4f
CPU: 3 PID: 4539 Comm: mount.nfs Not tainted 3.18.0-rc1-00013-g5b095e9 #3393
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
ffff880021499390 ffff8800381476a8 ffffffff81a534cf 0000000000000001
0000000000000000 ffff8800381476c8 ffffffff81097854 00000000000000d0
0000000000000018 ffff880038147718 ffffffff8118e4f3 0000000020479f00
Call Trace:
[<ffffffff81a534cf>] dump_stack+0x4f/0x7c
[<ffffffff81097854>] __might_sleep+0x114/0x180
[<ffffffff8118e4f3>] __kmalloc+0x1a3/0x280
[<ffffffffa00e31d8>] gss_stringify_acceptor+0x58/0xb0 [auth_rpcgss]
[<ffffffffa00e3185>] ? gss_stringify_acceptor+0x5/0xb0 [auth_rpcgss]
[<ffffffffa006b438>] rpcauth_stringify_acceptor+0x18/0x30 [sunrpc]
[<ffffffffa01b0469>] nfs4_proc_setclientid+0x199/0x380 [nfsv4]
[<ffffffffa01b04d0>] ? nfs4_proc_setclientid+0x200/0x380 [nfsv4]
[<ffffffffa01bdf1a>] nfs40_discover_server_trunking+0xda/0x150 [nfsv4]
[<ffffffffa01bde45>] ? nfs40_discover_server_trunking+0x5/0x150 [nfsv4]
[<ffffffffa01c0acf>] nfs4_discover_server_trunking+0x7f/0x2f0 [nfsv4]
[<ffffffffa01c8e24>] nfs4_init_client+0x104/0x2f0 [nfsv4]
[<ffffffffa01539b4>] nfs_get_client+0x314/0x3f0 [nfs]
[<ffffffffa0153780>] ? nfs_get_client+0xe0/0x3f0 [nfs]
[<ffffffffa01c83aa>] nfs4_set_client+0x8a/0x110 [nfsv4]
[<ffffffffa0069708>] ? __rpc_init_priority_wait_queue+0xa8/0xf0 [sunrpc]
[<ffffffffa01c9b2f>] nfs4_create_server+0x12f/0x390 [nfsv4]
[<ffffffffa01c1472>] nfs4_remote_mount+0x32/0x60 [nfsv4]
[<ffffffff81196489>] mount_fs+0x39/0x1b0
[<ffffffff81166145>] ? __alloc_percpu+0x15/0x20
[<ffffffff811b276b>] vfs_kern_mount+0x6b/0x150
[<ffffffffa01c1396>] nfs_do_root_mount+0x86/0xc0 [nfsv4]
[<ffffffffa01c1784>] nfs4_try_mount+0x44/0xc0 [nfsv4]
[<ffffffffa01549b7>] ? get_nfs_version+0x27/0x90 [nfs]
[<ffffffffa0161a2d>] nfs_fs_mount+0x47d/0xd60 [nfs]
[<ffffffff81a59c5e>] ? mutex_unlock+0xe/0x10
[<ffffffffa01606a0>] ? nfs_remount+0x430/0x430 [nfs]
[<ffffffffa01609c0>] ? nfs_clone_super+0x140/0x140 [nfs]
[<ffffffff81196489>] mount_fs+0x39/0x1b0
[<ffffffff81166145>] ? __alloc_percpu+0x15/0x20
[<ffffffff811b276b>] vfs_kern_mount+0x6b/0x150
[<ffffffff811b5830>] do_mount+0x210/0xbe0
[<ffffffff811b54ca>] ? copy_mount_options+0x3a/0x160
[<ffffffff811b651f>] SyS_mount+0x6f/0xb0
[<ffffffff81a5c852>] system_call_fastpath+0x12/0x17
Sleeping under the rcu_read_lock is bad. This patch fixes it by dropping
the rcu_read_lock before doing the allocation and then reacquiring it
and redoing the dereference before doing the copy. If we find that the
string has somehow grown in the meantime, we'll reallocate and try again.
Cc: <stable@vger.kernel.org> # v3.17+
Reported-by: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
1 parent f8ebf7a
extable.c
/*
* Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
*
* Copyright (C) 2004 Paul Mackerras, IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
#ifndef ARCH_HAS_SORT_EXTABLE
/*
* The exception table needs to be sorted so that the binary
* search that we use to find entries in it works properly.
* This is used both for the kernel exception table and for
* the exception tables of modules that get loaded.
*/
static int cmp_ex(const void *a, const void *b)
{
const struct exception_table_entry *x = a, *y = b;
/* avoid overflow */
if (x->insn > y->insn)
return 1;
if (x->insn < y->insn)
return -1;
return 0;
}
void sort_extable(struct exception_table_entry *start,
struct exception_table_entry *finish)
{
sort(start, finish - start, sizeof(struct exception_table_entry),
cmp_ex, NULL);
}
#ifdef CONFIG_MODULES
/*
* If the exception table is sorted, any referring to the module init
* will be at the beginning or the end.
*/
void trim_init_extable(struct module *m)
{
/*trim the beginning*/
while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {
m->extable++;
m->num_exentries--;
}
/*trim the end*/
while (m->num_exentries &&
within_module_init(m->extable[m->num_exentries-1].insn, m))
m->num_exentries--;
}
#endif /* CONFIG_MODULES */
#endif /* !ARCH_HAS_SORT_EXTABLE */
#ifndef ARCH_HAS_SEARCH_EXTABLE
/*
* Search one exception table for an entry corresponding to the
* given instruction address, and return the address of the entry,
* or NULL if none is found.
* We use a binary search, and thus we assume that the table is
* already sorted.
*/
const struct exception_table_entry *
search_extable(const struct exception_table_entry *first,
const struct exception_table_entry *last,
unsigned long value)
{
while (first <= last) {
const struct exception_table_entry *mid;
mid = ((last - first) >> 1) + first;
/*
* careful, the distance between value and insn
* can be larger than MAX_LONG:
*/
if (mid->insn < value)
first = mid + 1;
else if (mid->insn > value)
last = mid - 1;
else
return mid;
}
return NULL;
}
#endif
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