Matthew Wilcox willy@infradead.org writes:
On Tue, Apr 11, 2023 at 08:16:46PM -0700, Stefan Roesch wrote:
case PR_SET_VMA: error = prctl_set_vma(arg2, arg3, arg4, arg5); break; +#ifdef CONFIG_KSM
- case PR_SET_MEMORY_MERGE:
if (mmap_write_lock_killable(me->mm))return -EINTR;if (arg2) {int err = ksm_add_mm(me->mm);if (!err)ksm_add_vmas(me->mm);in the last version of this patch, you reported the error. Now you swallow the error. I have no idea which is correct, but you've changed the behaviour without explaining it, so I assume it's wrong.
I don't see how the error is swallowed in the arg2 case. If there is an error ksm_add_vmas is not executedd and at the end of the function the error is returned. Am I missing something?
} else {clear_bit(MMF_VM_MERGE_ANY, &me->mm->flags);}mmap_write_unlock(me->mm);break;- case PR_GET_MEMORY_MERGE:
if (arg2 || arg3 || arg4 || arg5)return -EINVAL;error = !!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags);break;Why do we need a GET? Just for symmetry, or is there an actual need for it?
There are three reasons: - For symmetry - The ksm sharing is inherited by child processes. This allows the test programs to verify that this is working. - For child processes it might be useful to have the ability to check if ksm sharing has been enabled