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System freezes with Kernel BUG at kernel/time/timer.c:1108 run_timer_softirq()
by Raghavendra. S Oct. 19, 2015

Oct. 19, 2015

Hi, In my x86 laptop I could observe random panic with Fatal exception in interrupt. We are testing Wi-Fi with our own driver issue occur randomly after 2-3 hours of testing. Panic is due to fatal except in interrupt and Kernel stack trace is run_timer_softirq()->__run_timers()->cascade()->BUG_ON(tbase_get_base(timer->base) != base); [image: Inline image 1] Any pointers to debug this will be of great help. -Raghu

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Why Completely Fair Scheduler(CFS) using Red-Black tree instead of Min-heap?
by venu gangireddy Oct. 18, 2015

Oct. 18, 2015

Hi, Currently, I am learning about CFS scheduler in linux, and I want to know reason about the data structure chooses in CFS implementation. CFS scheduler picks next process based on minimum virtual time and to get this value efficiently its using Red-Black tree(rbtree), using rbtree we will get minimum O(h) here h is height of rbtree. But, using min-heap we can get min virtual time process in O(1) time only. I just want to know why min-heap is not consider in CFS implementation and is there any difficulties using min-heap in kernel level? Thanks in advance. -- *Regards,* *Venugopal Reddy.*

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I have a large patch in the 2000 lines. What to do?
by Ivan Safonov Oct. 16, 2015

Oct. 16, 2015

Hi! I have a large patch in the 2000 lines, which replaces the macro BITn to BIT(n) in multiple files. Is it worth to split this patch into several parts? Is it sufficient to place the changes in each file in a separate part of patchset?

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parameter of module_init() and module_exit() must not be a macro
by Warlich, Christof Oct. 16, 2015

Oct. 16, 2015

I'd just like to get some feedback on the following issue and if the patch that I'm suggesting would be appropriate to be considered for upstream submission: While writing a driver template, I just came across an issue with the module_init() and module_exit() macros: They don't work properly when the parameter being passed to them is a macro itself. Here is a minimal example that shows the issue: $ cat test.c #include <linux/module.h> #define DRIVER_INIT test_init static int __init DRIVER_INIT(void) { return 0; } //module_init(test_init); // This works, ... module_init(DRIVER_INIT); // ... but this doesn't. Building the module gives the following errors: $ make -C /lib/modules/$(uname -r)/build MODULES=test M=$(pwd) modules make: Entering directory `/usr/src/linux-headers-3.13.0-65-generic' CC [M] /home/adwach13/tmp/module/tst.o In file included from /usr/src/linux-headers-3.13.0-65-generic/arch/x86/include/asm/ptrace.h:63:0, from /usr/src/linux-headers-3.13.0-65-generic/arch/x86/include/asm/alternative.h:8, from /usr/src/linux-headers-3.13.0-65-generic/arch/x86/include/asm/bitops.h:16, from include/linux/bitops.h:36, from include/linux/kernel.h:10, from include/linux/cache.h:4, from include/linux/time.h:4, from include/linux/stat.h:18, from include/linux/module.h:10, from /home/adwach13/tmp/module/tst.c:1: include/linux/init.h:298:6: error: 'init_module' aliased to undefined symbol 'DRIVER_INIT' int init_module(void) __attribute__((alias(#initfn))); ^ /home/adwach13/tmp/module/tst.c:8:1: note: in expansion of macro 'module_init' module_init(DRIVER_INIT); ^ make[1]: *** [/home/adwach13/tmp/module/tst.o] Error 1 make: *** [_module_/home/adwach13/tmp/module] Error 2 make: Leaving directory `/usr/src/linux-headers-3.13.0-65-generic' The reason for this behavior is because macro stringification is not done properly in the module_init() and module_exit() macro definitions in include/linux/init.h. But a fix would be easy: $ diff -Nau /usr/src/linux-headers-3.13.0-65-generic/include/linux/init.h.orig /usr/src/linux-headers-3.13.0-65-generic/include/linux/init.h --- /usr/src/linux-headers-3.13.0-65-generic/include/linux/init.h.orig 2015-10-15 11:40:36.300458826 +0200 +++ /usr/src/linux-headers-3.13.0-65-generic/include/linux/init.h 2015-10-15 11:42:05.370985262 +0200 @@ -291,17 +291,20 @@ #define security_initcall(fn) module_init(fn) +#define _STRINGIFY(x) #x +#define STRINGIFY(x) _STRINGIFY(x) + /* Each module must use one module_init(). */ #define module_init(initfn) \ static inline initcall_t __inittest(void) \ { return initfn; } \ - int init_module(void) __attribute__((alias(#initfn))); + int init_module(void) __attribute__((alias(STRINGIFY(initfn)))); /* This is only required if you want to be unloadable. */ #define module_exit(exitfn) \ static inline exitcall_t __exittest(void) \ { return exitfn; } \ - void cleanup_module(void) __attribute__((alias(#exitfn))); + void cleanup_module(void) __attribute__((alias(STRINGIFY(exitfn)))); #define __setup_param(str, unique_id, fn) /* nothing */ #define __setup(str, func) /* nothing */ What do you think: Is this patch worth to be suggested? Or is the current behavior intended?

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kernel panic
by jinzhao＠wingtech.com Oct. 16, 2015

Oct. 16, 2015

Dear all: I met a problem as below, what the function of walk_page_range?? Exception Class: Kernel (KE) PC is at [<ffffffc00017fc90>] walk_page_range+0x3c/0x314 Current Executing Process: [Binder_C, 3611][main, 354] Backtrace: [<ffffffc0009f21dc>] __do_kernel_fault.part.5+0x70/0x84 [<ffffffc0000942f4>] do_bad_area+0x90/0x94 [<ffffffc000094340>] do_translation_fault+0x30/0x4c [<ffffffc0000813fc>] do_mem_abort+0x38/0x98 [<ffffffc000083c58>] el1_da+0x1c/0x88 [<ffffffc0001eb3e0>] show_smap+0x88/0x284 [<ffffffc0001eb5e8>] show_pid_smap+0xc/0x18 [<ffffffc0001aefb8>] seq_read+0x1a4/0x40c [<ffffffc00018e75c>] vfs_read+0x88/0x170 [<ffffffc00018ebf0>] SyS_read+0x40/0x8c [<ffffffc000084308>] cpu_switch_to+0x48/0x4c [<ffffffffffffffff>] 0xffffffffffffffff Thanks! jinzhao(a)wingtech.cn

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Re: Kernelnewbies Digest, Vol 59, Issue 24
by Prasad Ram Oct. 12, 2015

Oct. 12, 2015

On 12 October 2015 at 21:30, <kernelnewbies-request(a)kernelnewbies.org> wrote: > Send Kernelnewbies mailing list submissions to > kernelnewbies(a)kernelnewbies.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > or, via email, send a message with subject or body 'help' to > kernelnewbies-request(a)kernelnewbies.org > > You can reach the person managing the list at > kernelnewbies-owner(a)kernelnewbies.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Kernelnewbies digest..." > > > Today's Topics: > > 1. RE: Your confirmation is required to join the Kernelnewbies > mailing list (Jennifer Lin) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 12 Oct 2015 11:17:33 +0800 > From: "Jennifer Lin" <jennifer.lin(a)dyna-image.com> > Subject: RE: Your confirmation is required to join the Kernelnewbies > mailing list > To: > < > kernelnewbies-confirm%2Ba4fac8166b063b0dfb8be9bed25b22e538ed5b32(a)kernelnewbies.org > > > > Cc: kernelnewbies(a)kernelnewbies.org > Message-ID: <561b264f.8944440a.d6caa.652a(a)mx.google.com> > Content-Type: text/plain; charset="utf-8" > > Hello All > > is okay > > > Best Regards, > Jennifer Lin > SW FAE > Sales & Marketing Dept. > DYNA IMAGE Corporation > Office: +886-2-2916-1968 #541 > Mobile: +886-10457099 > 8F, 233-2, Pao-Chiao Rd., Hsin-Tien, New Taipei City 23145, Taiwan > > > > -----Original Message----- > From: kernelnewbies-bounces(a)kernelnewbies.org [mailto: > kernelnewbies-bounces(a)kernelnewbies.org] On Behalf Of > kernelnewbies-confirm%2Ba4fac8166b063b0dfb8be9bed25b22e538ed5b32(a)kernelnewbies.org > Sent: Monday, October 12, 2015 11:06 AM > To: jennifer.lin(a)dyna-image.com > Subject: Your confirmation is required to join the Kernelnewbies mailing > list > > Mailing list subscription confirmation notice for mailing list > Kernelnewbies > > We have received a request from 223-136-106-25.emome-ip.hinet.net for > subscription of your email address, "jennifer.lin(a)dyna-image.com", to > the kernelnewbies(a)kernelnewbies.org mailing list. To confirm that you > want to be added to this mailing list, simply reply to this message, > keeping the Subject: header intact. Or visit this web page: > > > http://lists.kernelnewbies.org/mailman/confirm/kernelnewbies/a4fac8166b063b… > > > Or include the following line -- and only the following line -- in a > message to kernelnewbies-request(a)kernelnewbies.org: > > confirm a4fac8166b063b0dfb8be9bed25b22e538ed5b32 > > Note that simply sending a `reply' to this message should work from > most mail readers, since that usually leaves the Subject: line in the > right form (additional "Re:" text in the Subject: is okay). > > If you do not wish to be subscribed to this list, please simply > disregard this message. If you think you are being maliciously > subscribed to the list, or have any other questions, send them to > kernelnewbies-owner(a)kernelnewbies.org. > > > > > ------------------------------ > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies(a)kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > End of Kernelnewbies Digest, Vol 59, Issue 24 > ********************************************* >

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RE: Your confirmation is required to join the Kernelnewbies mailing list
by Jennifer Lin Oct. 12, 2015

Oct. 12, 2015

Hello All is okay Best Regards, Jennifer Lin SW FAE Sales & Marketing Dept. DYNA IMAGE Corporation Office: +886-2-2916-1968 #541 Mobile: +886-10457099 8F, 233-2, Pao-Chiao Rd., Hsin-Tien, New Taipei City 23145, Taiwan -----Original Message----- From: kernelnewbies-bounces(a)kernelnewbies.org [mailto:kernelnewbies-bounces@kernelnewbies.org] On Behalf Of kernelnewbies-confirm%2Ba4fac8166b063b0dfb8be9bed25b22e538ed5b32(a)kernelnewbies.org Sent: Monday, October 12, 2015 11:06 AM To: jennifer.lin(a)dyna-image.com Subject: Your confirmation is required to join the Kernelnewbies mailing list Mailing list subscription confirmation notice for mailing list Kernelnewbies We have received a request from 223-136-106-25.emome-ip.hinet.net for subscription of your email address, "jennifer.lin(a)dyna-image.com", to the kernelnewbies(a)kernelnewbies.org mailing list. To confirm that you want to be added to this mailing list, simply reply to this message, keeping the Subject: header intact. Or visit this web page: http://lists.kernelnewbies.org/mailman/confirm/kernelnewbies/a4fac8166b063b… Or include the following line -- and only the following line -- in a message to kernelnewbies-request(a)kernelnewbies.org: confirm a4fac8166b063b0dfb8be9bed25b22e538ed5b32 Note that simply sending a `reply' to this message should work from most mail readers, since that usually leaves the Subject: line in the right form (additional "Re:" text in the Subject: is okay). If you do not wish to be subscribed to this list, please simply disregard this message. If you think you are being maliciously subscribed to the list, or have any other questions, send them to kernelnewbies-owner(a)kernelnewbies.org.

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questions regarding PCIe
by Ramon Fried Oct. 9, 2015

Oct. 9, 2015

Hi. I need to write two PCIe drivers. One at the host PC and one on the device, which also runs Linux. Basically, the Host needs to map the device memory and initialize DMA access on that. On the Host side, I figured that I need to write an endpoint device, and follow the instructions described in Documentation/PCI/pci.txt. On the device side, I'm quite confused. What kind of driver is it ? Is there a good reference driver in the tree I can look at ? Thanks, Ramon

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efficient way to verify one memory block is only readable?
by mudongliang Oct. 9, 2015

Oct. 9, 2015

When I did some experiments about vtable, and modified the virtual method address myself, I found error report : "Segment fault". When I see the /proc/self/maps, vtable is in the readonly text segment. I almost forget the fact that vtables have been stored in readonly segment. So I have a question : how to effectively verify one memory block is only readable or writable? I think it's not efficient to check all the parts in /proc/maps. Does anyone have another efficient way to do this verification? Thanks in advance. - mudongliang

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Got wrongly (I hope) banned from eudyptula challenge
by Vinicius Tinti Oct. 9, 2015

Oct. 9, 2015

Hi, I think I got banned from Eudyptula Challenge because my last mail which I asked people to check if they received their answer from Little. Who could I ask to verify and see that I have not violated the terms in Little? Regards, Vinicius LAST MAIL: Hi, Is anyone stuck on task 8 too? I have sent again my files and notice that it is still processing September 5th. Could someone check? Regards, Vinicius -- Simplicity is the ultimate sophistication

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