On Wed, Sep 09, 2020 at 11:24:14AM -0700, Hugh Dickins wrote: > After overnight reflection, my own preference would be simply to > drop this patch. I think we are making altogether too much of a > fuss here over what was simply correct as plain put_page() > (and further from correct if we change it to leak the page in an > unforeseen circumstance). > > And if Alex's comment was not quite grammatically correct, never mind, > it said as much as was worth saying. I got more worried by his > placement of the "busy:" label, but that does appear to work correctly. > > There's probably a thousand places where put_page() is used, where > it would be troublesome if it were the final put_page(): this one > bothered you because you'd been looking at isolate_migratepages_block(), > and its necessary avoidance of lru_lock recursion on put_page(); > but let's just just leave this put_page() as is.
My problem with put_page() is that it's no longer the simple decrement-and-branch-to-slow-path-if-zero that it used to be. It has the awful devmap excrement in it so it really expands into a lot of code. I really wish that "feature" could be backed out again. It clearly wasn't ready for merge.
