Re: 1352 NUL bytes at the end of a page?

viro
2004-05-17T19:06:34Z

On Mon, May 17, 2004 at 11:39:58AM -0600, Steven Cole wrote:
> Yes, seven of the 52 references to mmap in the strace output met
> the above criteria:
>
> old_mmap(0x4015f000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x142000) = 0x4015f000
> old_mmap(0x40170000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x9000) = 0x40170000
> old_mmap(0x40180000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x9000) = 0x40180000
> old_mmap(0x40191000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x10000) = 0x40191000
> old_mmap(0x4019c000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x7000) = 0x4019c000
> old_mmap(0x401a0000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x3000) = 0x401a0000
> old_mmap(0x401af000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0xe000) = 0x401af000

Shared libraries. And no, those will never lead to any writes, no matter how
you modify them (MAP_PRIVATE). Which is the point, since that's where we
are doing relocations and we definitely do not want that to hit the disk ;-)

IOW, we can remove writes of dirtied mmap'ed pages from consideration.