Revision 85bd839983778fcd0c1c043327b14a046e979b39 authored by Gu Zheng on 10 June 2015, 18:14:43 UTC, committed by Linus Torvalds on 10 June 2015, 23:43:43 UTC
Izumi found the following oops when hot re-adding a node: BUG: unable to handle kernel paging request at ffffc90008963690 IP: __wake_up_bit+0x20/0x70 Oops: 0000 [#1] SMP CPU: 68 PID: 1237 Comm: rs:main Q:Reg Not tainted 4.1.0-rc5 #80 Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000 Series BIOS Version 1.87 04/28/2015 task: ffff880838df8000 ti: ffff880017b94000 task.ti: ffff880017b94000 RIP: 0010:[<ffffffff810dff80>] [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 RSP: 0018:ffff880017b97be8 EFLAGS: 00010246 RAX: ffffc90008963690 RBX: 00000000003c0000 RCX: 000000000000a4c9 RDX: 0000000000000000 RSI: ffffea101bffd500 RDI: ffffc90008963648 RBP: ffff880017b97c08 R08: 0000000002000020 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a0797c73800 R13: ffffea101bffd500 R14: 0000000000000001 R15: 00000000003c0000 FS: 00007fcc7ffff700(0000) GS:ffff880874800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc90008963690 CR3: 0000000836761000 CR4: 00000000001407e0 Call Trace: unlock_page+0x6d/0x70 generic_write_end+0x53/0xb0 xfs_vm_write_end+0x29/0x80 [xfs] generic_perform_write+0x10a/0x1e0 xfs_file_buffered_aio_write+0x14d/0x3e0 [xfs] xfs_file_write_iter+0x79/0x120 [xfs] __vfs_write+0xd4/0x110 vfs_write+0xac/0x1c0 SyS_write+0x58/0xd0 system_call_fastpath+0x12/0x76 Code: 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 45 f8 31 c0 48 8d 47 48 <48> 39 47 48 48 c7 45 e8 00 00 00 00 48 c7 45 f0 00 00 00 00 48 RIP [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 RSP <ffff880017b97be8> CR2: ffffc90008963690 Reproduce method (re-add a node):: Hot-add nodeA --> remove nodeA --> hot-add nodeA (panic) This seems an use-after-free problem, and the root cause is zone->wait_table was not set to *NULL* after free it in try_offline_node. When hot re-add a node, we will reuse the pgdat of it, so does the zone struct, and when add pages to the target zone, it will init the zone first (including the wait_table) if the zone is not initialized. The judgement of zone initialized is based on zone->wait_table: static inline bool zone_is_initialized(struct zone *zone) { return !!zone->wait_table; } so if we do not set the zone->wait_table to *NULL* after free it, the memory hotplug routine will skip the init of new zone when hot re-add the node, and the wait_table still points to the freed memory, then we will access the invalid address when trying to wake up the waiting people after the i/o operation with the page is done, such as mentioned above. Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Reported-by: Taku Izumi <izumi.taku@jp.fujitsu.com> Reviewed by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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clk-fractional-divider.c
/*
* Copyright (C) 2014 Intel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Adjustable fractional divider clock implementation.
* Output rate = (m / n) * parent_rate.
*/
#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/gcd.h>
#define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, hw)
static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_fractional_divider *fd = to_clk_fd(hw);
unsigned long flags = 0;
u32 val, m, n;
u64 ret;
if (fd->lock)
spin_lock_irqsave(fd->lock, flags);
val = clk_readl(fd->reg);
if (fd->lock)
spin_unlock_irqrestore(fd->lock, flags);
m = (val & fd->mmask) >> fd->mshift;
n = (val & fd->nmask) >> fd->nshift;
if (!n || !m)
return parent_rate;
ret = (u64)parent_rate * m;
do_div(ret, n);
return ret;
}
static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
struct clk_fractional_divider *fd = to_clk_fd(hw);
unsigned maxn = (fd->nmask >> fd->nshift) + 1;
unsigned div;
if (!rate || rate >= *prate)
return *prate;
div = gcd(*prate, rate);
while ((*prate / div) > maxn) {
div <<= 1;
rate <<= 1;
}
return rate;
}
static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_fractional_divider *fd = to_clk_fd(hw);
unsigned long flags = 0;
unsigned long div;
unsigned n, m;
u32 val;
div = gcd(parent_rate, rate);
m = rate / div;
n = parent_rate / div;
if (fd->lock)
spin_lock_irqsave(fd->lock, flags);
val = clk_readl(fd->reg);
val &= ~(fd->mmask | fd->nmask);
val |= (m << fd->mshift) | (n << fd->nshift);
clk_writel(val, fd->reg);
if (fd->lock)
spin_unlock_irqrestore(fd->lock, flags);
return 0;
}
const struct clk_ops clk_fractional_divider_ops = {
.recalc_rate = clk_fd_recalc_rate,
.round_rate = clk_fd_round_rate,
.set_rate = clk_fd_set_rate,
};
EXPORT_SYMBOL_GPL(clk_fractional_divider_ops);
struct clk *clk_register_fractional_divider(struct device *dev,
const char *name, const char *parent_name, unsigned long flags,
void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
u8 clk_divider_flags, spinlock_t *lock)
{
struct clk_fractional_divider *fd;
struct clk_init_data init;
struct clk *clk;
fd = kzalloc(sizeof(*fd), GFP_KERNEL);
if (!fd) {
dev_err(dev, "could not allocate fractional divider clk\n");
return ERR_PTR(-ENOMEM);
}
init.name = name;
init.ops = &clk_fractional_divider_ops;
init.flags = flags | CLK_IS_BASIC;
init.parent_names = parent_name ? &parent_name : NULL;
init.num_parents = parent_name ? 1 : 0;
fd->reg = reg;
fd->mshift = mshift;
fd->mmask = (BIT(mwidth) - 1) << mshift;
fd->nshift = nshift;
fd->nmask = (BIT(nwidth) - 1) << nshift;
fd->flags = clk_divider_flags;
fd->lock = lock;
fd->hw.init = &init;
clk = clk_register(dev, &fd->hw);
if (IS_ERR(clk))
kfree(fd);
return clk;
}
EXPORT_SYMBOL_GPL(clk_register_fractional_divider);
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