On 12/28/20 6:21 PM, Brian Geffon wrote:
> This looks good to me with a small comment.
>
>> if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
>> /* OOM: unable to split vma, just get accounts right */
>> - if (vm_flags & VM_ACCOUNT)
>> + if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP))
>> vm_acct_memory(new_len >> PAGE_SHIFT);
>
> Checking MREMAP_DONTUNMAP in the do_munmap path is unnecessary as
> MREMAP_DONTUNMAP will have already returned by this point.
In this code it is also used as err-path. In case move_page_tables()
fails to move all page tables or .mremap() callback fails, the new VMA
is unmapped.
IOW, MREMAP_DONTUNMAP returns under:
: if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) {
--
Dima
