IS_GLOBAL_INIT(9) Driver Basics IS_GLOBAL_INIT(9)NAME
is_global_init - check if a task structure is init
int is_global_init(struct task_struct * tsk);
Task structure to be checked.
Check if a task structure is the first user space task the kernel created.
1 if the task structure is init. 0 otherwise.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 IS_GLOBAL_INIT(9)
Check Out this Related Man Page
GET_USER_PAGES(9) Memory Management in Linux GET_USER_PAGES(9)NAME
get_user_pages - pin user pages in memory
int get_user_pages(struct task_struct * tsk, struct mm_struct * mm, unsigned long start, int nr_pages, int write, int force,
struct page ** pages, struct vm_area_struct ** vmas);
task_struct of target task
mm_struct of target mm
starting user address
number of pages from start to pin
whether pages will be written to by the caller
whether to force write access even if user mapping is readonly. This will result in the page being COWed even in MAP_SHARED mappings.
You do not want this.
array that receives pointers to the pages pinned. Should be at least nr_pages long. Or NULL, if caller only intends to ensure the pages
are faulted in.
array of pointers to vmas corresponding to each page. Or NULL if the caller does not require them.
Returns number of pages pinned. This may be fewer than the number requested. If nr_pages is 0 or negative, returns 0. If no pages were
pinned, returns -errno. Each page returned must be released with a put_page call when it is finished with. vmas will only remain valid
while mmap_sem is held.
Must be called with mmap_sem held for read or write.
get_user_pages walks a process's page tables and takes a reference to each struct page that each user address corresponds to at a given
instant. That is, it takes the page that would be accessed if a user thread accesses the given user virtual address at that instant.
This does not guarantee that the page exists in the user mappings when get_user_pages returns, and there may even be a completely different
page there in some cases (eg. if mmapped pagecache has been invalidated and subsequently re faulted). However it does guarantee that the
page won't be freed completely. And mostly callers simply care that the page contains data that was valid *at some point in time*.
Typically, an IO or similar operation cannot guarantee anything stronger anyway because locks can't be held over the syscall boundary.
If write=0, the page must not be written to. If the page is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must be
called after the page is finished with, and before put_page is called.
get_user_pages is typically used for fewer-copy IO operations, to get a handle on the memory by some means other than accesses via the user
virtual addresses. The pages may be submitted for DMA to devices or accessed via their kernel linear mapping (via the kmap APIs). Care
should be taken to use the correct cache flushing APIs.
See also get_user_pages_fast, for performance critical applications.
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 GET_USER_PAGES(9)
I know the following questions are noobish questions but I am asking them because I am confused about the basics of history behind UNIX and LINUX.
Ok onto business, my questions are-:
Was/Is UNIX ever an open source operating system ?
If UNIX was... (21 Replies)
Hello and thanks in advance for any help anyone can offer me
I'm trying to learn the find command and thought I was understanding it... Apparently I was wrong. I was doing compound searches and I started getting weird results with the -size test. I was trying to do a search on a 1G file owned by... (14 Replies)
i have installed quota on my centos 7 machine and its what im after (setting size limit on users, so they cant fill the hard drive)
i want to now make this part of my create user script for my sftp server so i want to do a echo and a read command so i capture the limit they enter... (0 Replies)
I need to write a shell script which opens a file and increments the version(text) within the file every time the script runs. For example:
$ cat docker_file.yml
So, I would like... (6 Replies)
We use DB2 v10.5 and using DBArtisan tool
Can someone please guide how to convert digits to binary numbers using db2 feature.
Ex> for number 9 , binary should be 1001 ( 8+1)
Any help appreciated. Thanks (2 Replies)
how to using tar with exclude directory and compress it using tar.Z
i only know how to exclude dir only with this command below:
tar -cvf /varios/restore/test.tar -X excludefile.txt /jfma/test1/
how to compress it using 1 command?
Please use CODE tags as... (6 Replies)
Quite an obscure question I think.
We have a rebuild process for remote sites that allows us to PXE rebuild a till (actually a PC with a touch screen and various fancy bits) running CentOS. The current CentOS5 tills work just fine with a tar image restore and some personalisation. Sadly,... (4 Replies)
I had recently learnt a bit of Docker(which provides containerization process).
Here are some of my learning points from it.
Let us start first with very basic question:
What is Docker:
Docker is a platform for sysadmins and developers to DEPLOY, DEVELOP and RUN applications ... (7 Replies)
What is the point of this? Whenever I close my shell it appends to the history file without adding this. I have never seen it overwrite my history file.
# When the shell exits, append to the history file instead of overwriting it
shopt -s histappend (3 Replies)
Hello... And thanks in advance for any help anyone can offer me
I was trying to work out the differences between displaying modify, access, and change times with the 'ls' command. Everything seems in order when I look at files, but the access time on a directory doesn't seem to change when I... (4 Replies)
I am having an issue here with CentOS release 6.6 (Final) that shows all of the space used up, but I can't tell where the space went.
Seemingly I am using up 100%, according to
Filesystem Size Used Avail Use% Mounted on... (27 Replies)
I'm trying to use a bash script for a psych experiment that involves listening to sound files and responding. If I have something like the code below, how can I make sure that a key press is assigned to RESPONSE only after the second echo statement?
for i in 1 2 3; do
... (10 Replies)
After the success of the jq - tool for parsing and manipulating JSON-Data someone wrote a tool called yq, which aims to be the same for YAML, what jq is for JSON. Seems to work fine. I'll definitely give it a chance in future.
... (1 Reply)
I am very pleased to announce that Dave Munro (gull04) is joining the Moderation Team, after being a very valuable member of UNIX.com for 15+ years.
Dave is an IT Consultant with 30 years of experience this year, has worked in many of the industry vertical market segments and has... (6 Replies)