Re: [PATCH] mm: put_and_wait_on_page_locked() while page is migrated

2018-11-26 Thread Tim Chen
On 11/25/2018 07:29 PM, Hugh Dickins wrote: >>Does somebody still have access to the customer load that triggered >> the horrible scaling issues before? > > Kan? Tim? > We don't have access to the workload know. Will ask the customer to see if they can test it. Thanks. Tim

Re: [PATCH] mm: put_and_wait_on_page_locked() while page is migrated

2018-11-25 Thread Hugh Dickins
On Sun, 25 Nov 2018, Linus Torvalds wrote: > On Sat, Nov 24, 2018 at 7:21 PM Hugh Dickins wrote: > > > > Linus, I'm addressing this patch to you because I see from Tim Chen's > > thread that it would interest you, and you were disappointed not to > > root cause the issue back then. I'm not pushin

Re: [PATCH] mm: put_and_wait_on_page_locked() while page is migrated

2018-11-25 Thread Linus Torvalds
On Sat, Nov 24, 2018 at 7:21 PM Hugh Dickins wrote: > > Linus, I'm addressing this patch to you because I see from Tim Chen's > thread that it would interest you, and you were disappointed not to > root cause the issue back then. I'm not pushing for you to fast-track > this into 4.20-rc, but I ex

Re: [PATCH] mm: put_and_wait_on_page_locked() while page is migrated

2018-11-24 Thread Andrea Arcangeli
On Sat, Nov 24, 2018 at 07:21:07PM -0800, Hugh Dickins wrote: > Waiting on a page migration entry has used wait_on_page_locked() all > along since 2006: but you cannot safely wait_on_page_locked() without > holding a reference to the page, and that extra reference is enough to > make migrate_page_m

[PATCH] mm: put_and_wait_on_page_locked() while page is migrated

2018-11-24 Thread Hugh Dickins
Waiting on a page migration entry has used wait_on_page_locked() all along since 2006: but you cannot safely wait_on_page_locked() without holding a reference to the page, and that extra reference is enough to make migrate_page_move_mapping() fail with -EAGAIN, when a racing task faults on the entr