On Thu, 10 Jan 2019, Vlastimil Babka wrote:
>
> For the record, anyone backporting this to older kernels should make
> sure to also include 605ca5ede764 ("mm/huge_memory.c: reorder operations
> in __split_huge_page_tail()") or they are in for a lot of fun, like me.
Thanks a lot for alerting us al
On 11/26/18 8:27 PM, 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_move_mapping() fail wi
On Tue, Nov 27, 2018 at 01:08:50PM -0800, Hugh Dickins wrote:
> On Tue, 27 Nov 2018, Mike Rapoport wrote:
> > On Mon, Nov 26, 2018 at 11:27:07AM -0800, Hugh Dickins wrote:
> > >
> > > +/*
> > > + * A choice of three behaviors for wait_on_page_bit_common():
> > > + */
> > > +enum behavior {
> > > +
On November 27, 2018 11:08:50 PM GMT+02:00, Hugh Dickins
wrote:
>On Tue, 27 Nov 2018, Mike Rapoport wrote:
>> On Mon, Nov 26, 2018 at 11:27:07AM -0800, Hugh Dickins wrote:
>> >
>> > +/*
>> > + * A choice of three behaviors for wait_on_page_bit_common():
>> > + */
>> > +enum behavior {
>> > +
On Tue, 27 Nov 2018, Mike Rapoport wrote:
> On Mon, Nov 26, 2018 at 11:27:07AM -0800, Hugh Dickins wrote:
> >
> > +/*
> > + * A choice of three behaviors for wait_on_page_bit_common():
> > + */
> > +enum behavior {
> > + EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
> > +
On Tue, Nov 27, 2018 at 12:58:48PM +0200, Mike Rapoport wrote:
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 81adec8ee02c..575e16c037ca 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1049,25 +1056,44 @@ static void wake_up_page(struct page *page, int bit)
> > wake_up_page
On Tue, Nov 27, 2018 at 8:49 AM Christopher Lameter wrote:
>
> A process has no refcount on a page struct and is waiting for it to become
> unlocked? Why? Should it not simply ignore that page and continue?
The problem isn't that you can just "continue".
You need to *retry*.
And you can't just
On Tue 27-11-18 16:49:47, Cristopher Lameter wrote:
> On Tue, 27 Nov 2018, Mike Rapoport wrote:
>
> > > * @page: The page to wait for.
> > > *
> > > * The caller should hold a reference on @page. They expect the page to
> > > * become unlocked relatively soon, but do not wish to hold up migra
On Tue, 27 Nov 2018, Mike Rapoport wrote:
> > * @page: The page to wait for.
> > *
> > * The caller should hold a reference on @page. They expect the page to
> > * become unlocked relatively soon, but do not wish to hold up migration
> > * (for example) by holding the reference while waiting
On Mon, Nov 26, 2018 at 11:27:07AM -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
On Mon, Nov 26, 2018 at 12:53:51PM -0800, Matthew Wilcox wrote:
> On Mon, Nov 26, 2018 at 11:27:07AM -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
On 11/26/18 8:27 PM, 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_move_mapping() fail wi
On Mon, Nov 26, 2018 at 11:27:07AM -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
On Mon 26-11-18 11:27:07, Hugh Dickins wrote:
[...]
> @@ -1049,25 +1056,44 @@ static void wake_up_page(struct page *page, int bit)
> wake_up_page_bit(page, bit);
> }
>
> +/*
> + * A choice of three behaviors for wait_on_page_bit_common():
> + */
> +enum behavior {
> + EXCLUSIVE, /
On Mon, Nov 26, 2018 at 11:27 AM Hugh Dickins wrote:
>
> +enum behavior {
> + EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
> +* __lock_page() waiting on then setting PG_locked.
> +*/
> + SHARED, /* Hold re
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
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