Re: [Crash-utility] [PATCH 1/1] fix left bit-shift overflow in __exclude_unnecessary_pages()

Hi Alex, +cc kexec list (the right one for makedumpfile patch)

-----Original Message----- > Whenever the variables compound_order or private become greater than > 31, left bit-shift of 1 overflows, and nr_pages becomes zero. If nr_pages > becomes 0 and pages are being excluded at the end of the PFN loop, the > else branch of the last if statement is entered and pfn is decremented by > 1 because nr_pages is 0. Finally, this causes the loop variable pfn to > be assigned the same value as before when the next loop iteration begins > which results in an infinite loop. > > This issue appeared on s390 64bit architecture with a dump of 16GB RAM. The patch looks good to me, but just out of curiosity, when do the compound_order or private become greater than 31 on s390? Thanks, Kazu