On i686 PAE enabled machine the contiguous physical area could be large and it can cause triming down variables in below calculation in read_vmcore() and mmap_vmcore(): tsz = min_t(size_t, m->offset + m->size - *fpos, buflen); Then the real size passed down is not correct any more. Suppose m->offset + m->size - *fpos being truncated to 0, buflen >0 then we will get tsz = 0. It is of course not an expected result. During out test there are two problems caused by it: 1) read_vmcore will refuse to continue so makedumpfile fails. 2) mmap_vmcore will trigger BUG_ON() in remap_pfn_range(). Use min_lt instead so that the variables are not truncated. Signed-off-by: Baoquan He Signed-off-by: Dave Young --- fs/proc/vmcore.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- linux.orig/fs/proc/vmcore.c +++ linux/fs/proc/vmcore.c @@ -231,7 +231,8 @@ static ssize_t __read_vmcore(char *buffe list_for_each_entry(m, &vmcore_list, list) { if (*fpos < m->offset + m->size) { - tsz = min_t(size_t, m->offset + m->size - *fpos, buflen); + tsz = (size_t)min_lt(m->offset + m->size - *fpos, + buflen); start = m->paddr + *fpos - m->offset; tmp = read_from_oldmem(buffer, tsz, &start, userbuf); if (tmp < 0) @@ -461,7 +462,7 @@ static int mmap_vmcore(struct file *file if (start < m->offset + m->size) { u64 paddr = 0; - tsz = min_t(size_t, m->offset + m->size - start, size); + tsz = (size_t)min_lt(m->offset + m->size - start, size); paddr = m->paddr + start - m->offset; if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len, paddr >> PAGE_SHIFT, tsz,