#undef TRACE_SYSTEM
#define TRACE_SYSTEM pagemap

#if !defined(_TRACE_PAGEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_PAGEMAP_H

#include <linux/tracepoint.h>
#include <linux/mm.h>

#define	PAGEMAP_MAPPED		0x0001u
#define PAGEMAP_ANONYMOUS	0x0002u
#define PAGEMAP_FILE		0x0004u
#define PAGEMAP_SWAPCACHE	0x0008u
#define PAGEMAP_SWAPBACKED	0x0010u
#define PAGEMAP_MAPPEDDISK	0x0020u
#define PAGEMAP_BUFFERS		0x0040u

#define trace_pagemap_flags(page) ( \
	(PageAnon(page)		? PAGEMAP_ANONYMOUS  : PAGEMAP_FILE) | \
	(page_mapped(page)	? PAGEMAP_MAPPED     : 0) | \
	(PageSwapCache(page)	? PAGEMAP_SWAPCACHE  : 0) | \
	(PageSwapBacked(page)	? PAGEMAP_SWAPBACKED : 0) | \
	(PageMappedToDisk(page)	? PAGEMAP_MAPPEDDISK : 0) | \
	(page_has_private(page) ? PAGEMAP_BUFFERS    : 0) \
	)

TRACE_EVENT(mm_lru_insertion,

	TP_PROTO(
		struct page *page,
		int lru
	),

	TP_ARGS(page, lru),

	TP_STRUCT__entry(
		__field(struct page *,	page	)
		__field(unsigned long,	pfn	)
		__field(int,		lru	)
		__field(unsigned long,	flags	)
	),

	TP_fast_assign(
		__entry->page	= page;
		__entry->pfn	= page_to_pfn(page);
		__entry->lru	= lru;
		__entry->flags	= trace_pagemap_flags(page);
	),

	/* Flag format is based on page-types.c formatting for pagemap */
	TP_printk("page=%p pfn=%lu lru=%d flags=%s%s%s%s%s%s",
			__entry->page,
			__entry->pfn,
			__entry->lru,
			__entry->flags & PAGEMAP_MAPPED		? "M" : " ",
			__entry->flags & PAGEMAP_ANONYMOUS	? "a" : "f",
			__entry->flags & PAGEMAP_SWAPCACHE	? "s" : " ",
			__entry->flags & PAGEMAP_SWAPBACKED	? "b" : " ",
			__entry->flags & PAGEMAP_MAPPEDDISK	? "d" : " ",
			__entry->flags & PAGEMAP_BUFFERS	? "B" : " ")
);

TRACE_EVENT(mm_lru_activate,

	TP_PROTO(struct page *page),

	TP_ARGS(page),

	TP_STRUCT__entry(
		__field(struct page *,	page	)
		__field(unsigned long,	pfn	)
	),

	TP_fast_assign(
		__entry->page	= page;
		__entry->pfn	= page_to_pfn(page);
	),

	/* Flag format is based on page-types.c formatting for pagemap */
	TP_printk("page=%p pfn=%lu", __entry->page, __entry->pfn)

);

#endif /* _TRACE_PAGEMAP_H */

/* This part must be outside protection */
#include <trace/define_trace.h>
e/uapi/xen/evtchn.h?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/include/uapi/xen/evtchn.h'>
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/include?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>include</a>/<a href='/cgit.cgi/linux/net-next.git/log/include/uapi?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>uapi</a>/<a href='/cgit.cgi/linux/net-next.git/log/include/uapi/xen?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>xen</a>/<a href='/cgit.cgi/linux/net-next.git/log/include/uapi/xen/evtchn.h?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927'>evtchn.h</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/include/uapi/xen/evtchn.h?h=nds-private-remove&amp;id=789ea12500e5ce3911d0a6a822277c3133451927&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
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<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/batman-adv/gateway_client.h?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/batman-adv/gateway_client.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/batman-adv/gateway_client.h?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/batman-adv/gateway_client.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/batman-adv/gateway_client.h?h=nds-private-remove&amp;id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/batman-adv/gateway_client.h?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/batman-adv/gateway_client.h')</div><table summary='diffstat' class='diffstat'>