Re: kern/55658: rumpvfs:t_etfs triggers bug in ufs_balloc_range() for 16KB page

[Chuck Silvers <chuq%chuq.com@localhost>]

The following reply was made to PR kern/55658; it has been noted by GNATS.

From: Chuck Silvers <chuq%chuq.com@localhost>
To: Rin Okuyama <rokuyama.rk%gmail.com@localhost>
Cc: gnats-bugs%netbsd.org@localhost
Subject: Re: kern/55658: rumpvfs:t_etfs triggers bug in ufs_balloc_range()
 for 16KB page
Date: Mon, 21 Sep 2020 00:42:20 -0700

 On Wed, Sep 16, 2020 at 01:09:23AM +0900, Rin Okuyama wrote:
 > Does this patch seem OK to you? Is there anything else to be checked
 > before commit?
 
 The one thing that I can think of to be concerned about is that
 now that we track page dirtiness via the radix tree tag,
 we have to make sure that a clean page is not mapped writable,
 so it would be good to have an assertion in ubc_fault_page() like:
 
 	KASSERT((access_type & VM_PROT_WRITE) == 0 ||
 		uvm_pagegetdirty(pg) != UVM_PAGE_STATUS_CLEAN);
 
 -Chuck