10 Jun, 2020
2 commits
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Now the last users of show_stack() got converted to use an explicit log
level, show_stack_loglvl() can drop it's redundant suffix and become once
again well known show_stack().Signed-off-by: Dmitry Safonov
Signed-off-by: Andrew Morton
Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com
Signed-off-by: Linus Torvalds -
Align the last users of show_stack() by KERN_DEFAULT as the surrounding
headers/messages.Signed-off-by: Dmitry Safonov
Signed-off-by: Andrew Morton
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Will Deacon
Link: http://lkml.kernel.org/r/20200418201944.482088-50-dima@arista.com
Signed-off-by: Linus Torvalds
07 Nov, 2019
1 commit
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In the current code, we use the atomic_cmpxchg() to serialize the output
of the dump_stack(), but this implementation suffers the thundering herd
problem. We have observed such kind of livelock on a Marvell cn96xx
board(24 cpus) when heavily using the dump_stack() in a kprobe handler.
Actually we can let the competitors to wait for the releasing of the
lock before jumping to atomic_cmpxchg(). This will definitely mitigate
the thundering herd problem. Thanks Linus for the suggestion.[akpm@linux-foundation.org: fix comment]
Link: http://lkml.kernel.org/r/20191030031637.6025-1-haokexin@gmail.com
Fixes: b58d977432c8 ("dump_stack: serialize the output from dump_stack()")
Signed-off-by: Kevin Hao
Suggested-by: Linus Torvalds
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Mar, 2018
1 commit
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dump_stack related stuff should belong to lib/dump_stack.c thus move them
there. Also conditionally compile lib/dump_stack.c since dump_stack code
does not make sense if printk is disabled.Link: http://lkml.kernel.org/r/20180213072834.GA24784@dhcp-128-65.nay.redhat.com
To: Steven Rostedt
Cc: linux-kernel@vger.kernel.org
Cc: akpm@linux-foundation.org
Cc: Andi Kleen
Signed-off-by: Dave Young
Suggested-by: Steven Rostedt
Suggested-by: Sergey Senozhatsky
Reviewed-by: Sergey Senozhatsky
Signed-off-by: Petr Mladek
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
02 Mar, 2017
1 commit
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We are going to split out of , which
will have to be picked up from other headers and a couple of .c files.Create a trivial placeholder file that just
maps to to make this patch obviously correct and
bisectable.Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
06 Feb, 2016
1 commit
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Some servers experienced fatal deadlocks because of a combination of
bugs, leading to multiple cpus calling dump_stack().The checksumming bug was fixed in commit 34ae6a1aa054 ("ipv6: update
skb->csum when CE mark is propagated").The second problem is a faulty locking in dump_stack()
CPU1 runs in process context and calls dump_stack(), grabs dump_lock.
CPU2 receives a TCP packet under softirq, grabs socket spinlock, and
call dump_stack() from netdev_rx_csum_fault().dump_stack() spins on atomic_cmpxchg(&dump_lock, -1, 2), since
dump_lock is owned by CPU1While dumping its stack, CPU1 is interrupted by a softirq, and happens
to process a packet for the TCP socket locked by CPU2.CPU1 spins forever in spin_lock() : deadlock
Stack trace on CPU1 looked like :
NMI backtrace for cpu 1
RIP: _raw_spin_lock+0x25/0x30
...
Call Trace:
tcp_v6_rcv+0x243/0x620
ip6_input_finish+0x11f/0x330
ip6_input+0x38/0x40
ip6_rcv_finish+0x3c/0x90
ipv6_rcv+0x2a9/0x500
process_backlog+0x461/0xaa0
net_rx_action+0x147/0x430
__do_softirq+0x167/0x2d0
call_softirq+0x1c/0x30
do_softirq+0x3f/0x80
irq_exit+0x6e/0xc0
smp_call_function_single_interrupt+0x35/0x40
call_function_single_interrupt+0x6a/0x70
printk+0x4d/0x4f
printk_address+0x31/0x33
print_trace_address+0x33/0x3c
print_context_stack+0x7f/0x119
dump_trace+0x26b/0x28e
show_trace_log_lvl+0x4f/0x5c
show_stack_log_lvl+0x104/0x113
show_stack+0x42/0x44
dump_stack+0x46/0x58
netdev_rx_csum_fault+0x38/0x3c
__skb_checksum_complete_head+0x6e/0x80
__skb_checksum_complete+0x11/0x20
tcp_rcv_established+0x2bd5/0x2fd0
tcp_v6_do_rcv+0x13c/0x620
sk_backlog_rcv+0x15/0x30
release_sock+0xd2/0x150
tcp_recvmsg+0x1c1/0xfc0
inet_recvmsg+0x7d/0x90
sock_recvmsg+0xaf/0xe0
___sys_recvmsg+0x111/0x3b0
SyS_recvmsg+0x5c/0xb0
system_call_fastpath+0x16/0x1bFixes: b58d977432c8 ("dump_stack: serialize the output from dump_stack()")
Signed-off-by: Eric Dumazet
Cc: Alex Thorlton
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 May, 2014
1 commit
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As requested by Linus add explicit __visible to the asmlinkage users.
This marks functions visible to assembler.Tree sweep for rest of tree.
Signed-off-by: Andi Kleen
Link: http://lkml.kernel.org/r/1398984278-29319-4-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin
07 Aug, 2013
1 commit
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dump_stack is used from assembler code, so make it visible.
Signed-off-by: Andi Kleen
Link: http://lkml.kernel.org/r/1375740170-7446-15-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin
04 Jul, 2013
1 commit
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Add functionality to serialize the output from dump_stack() to avoid
mangling of the output when dump_stack is called simultaneously from
multiple cpus.[akpm@linux-foundation.org: fix comment indenting, avoid inclusion of files - use where possiblem fix uniprocessor build (__dump_stack undefined), remove unneeded ifdef around smp.h inclusion]
Signed-off-by: Alex Thorlton
Reported-by: Russ Anderson
Reviewed-by: Robin Holt
Cc: Vineet Gupta
Cc: David S. Miller
Cc: Richard Kuo
Cc: Jesper Nilsson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 May, 2013
1 commit
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Both dump_stack() and show_stack() are currently implemented by each
architecture. show_stack(NULL, NULL) dumps the backtrace for the
current task as does dump_stack(). On some archs, dump_stack() prints
extra information - pid, utsname and so on - in addition to the
backtrace while the two are identical on other archs.The usages in arch-independent code of the two functions indicate
show_stack(NULL, NULL) should print out bare backtrace while
dump_stack() is used for debugging purposes when something went wrong,
so it does make sense to print additional information on the task which
triggered dump_stack().There's no reason to require archs to implement two separate but mostly
identical functions. It leads to unnecessary subtle information.This patch expands the dummy fallback dump_stack() implementation in
lib/dump_stack.c such that it prints out debug information (taken from
x86) and invokes show_stack(NULL, NULL) and drops arch-specific
dump_stack() implementations in all archs except blackfin. Blackfin's
dump_stack() does something wonky that I don't understand.Debug information can be printed separately by calling
dump_stack_print_info() so that arch-specific dump_stack()
implementation can still emit the same debug information. This is used
in blackfin.This patch brings the following behavior changes.
* On some archs, an extra level in backtrace for show_stack() could be
printed. This is because the top frame was determined in
dump_stack() on those archs while generic dump_stack() can't do that
reliably. It can be compensated by inlining dump_stack() but not
sure whether that'd be necessary.* Most archs didn't use to print debug info on dump_stack(). They do
now.An example WARN dump follows.
WARNING: at kernel/workqueue.c:4841 init_workqueues+0x35/0x505()
Hardware name: empty
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #9
0000000000000009 ffff88007c861e08 ffffffff81c614dc ffff88007c861e48
ffffffff8108f50f ffffffff82228240 0000000000000040 ffffffff8234a03c
0000000000000000 0000000000000000 0000000000000000 ffff88007c861e58
Call Trace:
[] dump_stack+0x19/0x1b
[] warn_slowpath_common+0x7f/0xc0
[] warn_slowpath_null+0x1a/0x20
[] init_workqueues+0x35/0x505
...v2: CPU number added to the generic debug info as requested by s390
folks and dropped the s390 specific dump_stack(). This loses %ksp
from the debug message which the maintainers think isn't important
enough to keep the s390-specific dump_stack() implementation.dump_stack_print_info() is moved to kernel/printk.c from
lib/dump_stack.c. Because linkage is per objecct file,
dump_stack_print_info() living in the same lib file as generic
dump_stack() means that archs which implement custom dump_stack()
- at this point, only blackfin - can't use dump_stack_print_info()
as that will bring in the generic version of dump_stack() too. v1
The v1 patch broke build on blackfin due to this issue. The build
breakage was reported by Fengguang Wu.Signed-off-by: Tejun Heo
Acked-by: David S. Miller
Acked-by: Vineet Gupta
Acked-by: Jesper Nilsson
Acked-by: Vineet Gupta
Acked-by: Martin Schwidefsky [s390 bits]
Cc: Heiko Carstens
Cc: Mike Frysinger
Cc: Fengguang Wu
Cc: Bjorn Helgaas
Cc: Sam Ravnborg
Acked-by: Richard Kuo [hexagon bits]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Mar, 2012
1 commit
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For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.Signed-off-by: Paul Gortmaker
17 Apr, 2005
1 commit
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.Let it rip!
