Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-08 Thread Matthew Wilcox
On Tue, Jan 08, 2019 at 01:26:49PM -0800, Andrew Morton wrote: > On Tue, 8 Jan 2019 12:26:35 -0800 Matthew Wilcox wrote: > > > > Would it be excessively cautious to put a WARN_ON_ONCE() in there for a > > > while? > > > > I think it would ... it'd get in the way of a subsequent patch to store >

Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-08 Thread Andrew Morton
On Tue, 8 Jan 2019 12:26:35 -0800 Matthew Wilcox wrote: > > Would it be excessively cautious to put a WARN_ON_ONCE() in there for a > > while? > > I think it would ... it'd get in the way of a subsequent patch to store > only head pages in the page cache. OK, shall grab. Perhaps the changelog

Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-08 Thread Matthew Wilcox
On Mon, Jan 07, 2019 at 03:09:04PM -0800, Andrew Morton wrote: > On Mon, 7 Jan 2019 14:39:35 -0800 Matthew Wilcox wrote: > > > On Mon, Jan 07, 2019 at 02:33:19PM -0800, Andrew Morton wrote: > > > On Mon, 7 Jan 2019 12:02:24 -0800 Matthew Wilcox > > > wrote: > > > > > > > After we establish a

Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-07 Thread Andrew Morton
On Mon, 7 Jan 2019 14:39:35 -0800 Matthew Wilcox wrote: > On Mon, Jan 07, 2019 at 02:33:19PM -0800, Andrew Morton wrote: > > On Mon, 7 Jan 2019 12:02:24 -0800 Matthew Wilcox > > wrote: > > > > > After we establish a reference on the page, we check the pointer continues > > > to be in the corr

Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-07 Thread Matthew Wilcox
On Mon, Jan 07, 2019 at 02:33:19PM -0800, Andrew Morton wrote: > On Mon, 7 Jan 2019 12:02:24 -0800 Matthew Wilcox wrote: > > > After we establish a reference on the page, we check the pointer continues > > to be in the correct position in i_pages. There's no need to check the > > page->mapping

Re: [PATCH] mm: Remove redundant test from find_get_pages_contig

2019-01-07 Thread Andrew Morton
On Mon, 7 Jan 2019 12:02:24 -0800 Matthew Wilcox wrote: > After we establish a reference on the page, we check the pointer continues > to be in the correct position in i_pages. There's no need to check the > page->mapping or page->index afterwards; if those can change after we've > got the refe