[Question] detach_vmas_to_be_unmapped

From: akuster
Date: Fri Feb 16 2007 - 16:40:49 EST


I am a bit confused on why the vm start and end address where swapped in arch_unmap_area and arch_unmap_area_topdown functions after the official Avoiding mmap fragmentation ( 1363c3cd8603a913a27e2995dccbd70d5312d8e6 ) patch.

Prior to this patch arch_unmap_area() used area->vm_start and arch_unmap_area_topdown used area->vm_end after the patch the following change showed up.

if (mm->unmap_area == arch_unmap_area)
addr = prev ? prev->vm_start : mm->mmap_base;
addr = vma ? vma->vm_end : mm->mmap_base;

Using Wolfgang Wander's leakme.c test, I get the same results seen with his original "Avoiding mmap fragmentation" patch as I do after swapping the start & end address in the above code segment.

Is it just a typo in the official patch or am I missing the much bigger picture?

Note: I have only run this on an Pentium4 with 1GiG memory.



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