mmap locked doesn't return

From: Sagar Borikar
Date: Mon Jan 23 2012 - 10:44:17 EST


Hi,


We are observing that mmap when called with MAP_SHARED and MAP_LOCKED
flags on the disk which has the bad sectors, doesn't return either
success or failure and gets stuck somewhere in mmap routine. Disk
replacement is the obvious solution but the question is what makes
mmap not to return failure?
Individual mapping works fine i.e. on the same disk at same offset
when mmap is invoked with MAP_SHARED or MAP_LOCKED the call succeeds
but when they both are clubbed together, it doesn't return anything.

strace output snippet

open("/dev/dm-4p2", O_RDWR) = 3
mmap(NULL, 10485760, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_LOCKED, 3, 0x4000000


setup:

2.6.23 LST kernel
Westmere platform - 4 socket cpu
RAM -192GB


Thanks
Sagar
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