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    <p>Each row in <code>/proc/$PID/maps</code> describes a region of contiguous virtual memory in a process or thread. Each row has the following fields:</p> <pre><code>address perms offset dev inode pathname 08048000-08056000 r-xp 00000000 03:0c 64593 /usr/sbin/gpm </code></pre> <ul> <li><strong>address</strong> - This is the starting and ending address of the region in the process's address space</li> <li><strong>permissions</strong> - This describes how pages in the region can be accessed. There are four different permissions: read, write, execute, and shared. If read/write/execute are disabled, a '-' will appear instead of the 'r'/'w'/'x'. If a region is not shared, it is private, so a 'p' will appear instead of an 's'. If the process attempts to access memory in a way that is not permitted, a segmentation fault is generated. Permissions can be changed using the <code>mprotect</code> system call.</li> <li><strong>offset</strong> - If the region was mapped from a file (using <code>mmap</code>), this is the offset in the file where the mapping begins. If the memory was not mapped from a file, it's just 0.</li> <li><strong>device</strong> - If the region was mapped from a file, this is the major and minor device number (in hex) where the file lives.</li> <li><strong>inode</strong> - If the region was mapped from a file, this is the file number.</li> <li><strong>pathname</strong> - If the region was mapped from a file, this is the name of the file. This field is blank for anonymous mapped regions. There are also special regions with names like <code>[heap]</code>, <code>[stack]</code>, or <code>[vdso]</code>. <code>[vdso]</code> stands for virtual dynamic shared object. It's used by system calls to switch to kernel mode. <a href="http://www.trilithium.com/johan/2005/08/linux-gate/" rel="noreferrer">Here's a good article about it.</a></li> </ul> <p>You might notice a lot of anonymous regions. These are usually created by <code>mmap</code> but are not attached to any file. They are used for a lot of miscellaneous things like shared memory or buffers not allocated on the heap. For instance, I think the pthread library uses anonymous mapped regions as stacks for new threads.</p>
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    1. COYes the pthreads are allocating 8Mb blocks for a stack with a smaller section for stack overflow detection(i think). So each pthread created, by default, allocates an inode 0 memory region of 8Mb and a inode 0 region of 4Kb.
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