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a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=2OwXVqhp2XgA:10 a=GoEa3M9JfhUA:10 a=yPCof4ZbAAAA:8 a=hqxEFHVobavvttKUrIwA:9 cc=ntf awl=host:12066 X-Proofpoint-GUID: z_ePvDpij-gQ71sGK3MY0PIq9gmheCzp X-Proofpoint-ORIG-GUID: z_ePvDpij-gQ71sGK3MY0PIq9gmheCzp X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDEyMyBTYWx0ZWRfXyPV5IbfNP9kZ UDpEi7YG4O7Pl1l85He7lr4YGeHwKdlEsvN+HhkPer6mpu96ZdqCp/Gg+VzZG+JherA65evZYXs V9W4U/kpUd5JBeQi1KmwkOfhXTA7NCa7Xpc1NYQCH2on+jB4+kn3SeQTaBgRxkKt+Hw6BOmwtWV G+B0qBYGCh2t0Asypr2JjbLhT42j7Fm1C+tYg048ZOhpqoLltAagz0pL6/9FDlKiCSHS+O7Jwl/ 81680V6oknMky+uSHFZBWUDib2z4HieMAvlTtrEQMh0OCEgCLO7JXFAQzg1rSuYO9/SdU138Gp4 6kbRPspqDwnq6L/cEFZWLBePVGI+z/bTZaO1Y08VyRZAyNHxRDwW6DAdN88rHp9MIasmFOPfS/5 Bp/Itm99IPKjCc0wpUvwOJAsLUJ+cIQdlzszVz7A9oZh94PWemBzu1HkQz15fM5uLL37sETO Content-Type: text/plain; charset="utf-8" There is pre-existing logic that appears to be undocumented for an mremap() shrink operation, where it turns out that the usual 'input range must span a single mapping' requirement no longer applies. In fact, it turns out that the input range specified by [old_address, old_address + old_size) may span any number of mappings. If shrinking in-place (that is, neither the MREMAP_FIXED nor MREMAP_DONTUNMAP flags are specified), then the new span may also span any number of VMAs - [old_address, old_address + new_size). If shrinking and moving, the range specified by [old_address, old_address + new_size) must span a single VMA. There must be at least one VMA contained within the [old_address, old_address + old_size) range, and old_address must be within the range of a VMA. Explicitly document this. Signed-off-by: Lorenzo Stoakes --- man/man2/mremap.2 | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/man/man2/mremap.2 b/man/man2/mremap.2 index 6ba51310c..631c835b8 100644 --- a/man/man2/mremap.2 +++ b/man/man2/mremap.2 @@ -48,8 +48,35 @@ The .B MREMAP_DONTUNMAP flag may be specified. .P -If the operation is not -simply moving mappings, +Equally, if the operation performs a shrink, +that is if +.I old_size +is greater than +.IR new_size , +then +.I old_size +may also span multiple mappings +which do not have to be +adjacent to one another. +If this shrink is performed +in-place, +that is, +neither +.BR MREMAP_FIXED , +nor +.B MREMAP_DONTUNMAP +are specified, +.I new_size +may also span multiple VMAs. +However, if the range is moved, +then +.I new_size +must span only a single mapping. +.P +If the operation is neither a +.B MREMAP_FIXED +move +nor a shrink, then .I old_size must span only a single mapping. --=20 2.50.1