From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: alex.shi@linux.alibaba.com, cai@lca.pw, hannes@cmpxchg.org,
hughd@google.com, linux-mm@kvack.org, mhocko@suse.com,
mike.kravetz@oracle.com, mm-commits@vger.kernel.org,
shakeelb@google.com, shy828301@gmail.com, stable@vger.kernel.org,
torvalds@linux-foundation.org
Subject: Re: [patch 04/15] shmem: shmem_writepage() split unlikely i915 THP
Date: Sat, 19 Sep 2020 05:44:08 +0100 [thread overview]
Message-ID: <20200919044408.GL32101@casper.infradead.org> (raw)
In-Reply-To: <20200919042009.bomzxmrg7%akpm@linux-foundation.org>
On Fri, Sep 18, 2020 at 09:20:09PM -0700, Andrew Morton wrote:
> LRU page reclaim always splits the shmem huge page first: I'd prefer not
> to demand that of i915, so check and split compound in shmem_writepage().
Sorry for not checking this earlier, but I don't think this is right.
for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) {
...
if (!page_mapped(page) && clear_page_dirty_for_io(page)) {
...
ret = mapping->a_ops->writepage(page, &wbc);
so we cleared the dirty bit on the entire hugepage, but then split
it after clearing the dirty bit, so the subpages are now not dirty.
I think we'll lose writes as a result? At least we won't swap pages
out that deserve to be paged out.
>
> - VM_BUG_ON_PAGE(PageCompound(page), page);
> + /*
> + * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force",
> + * then drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
> + * and its shmem_writeback() needs them to be split when swapping.
> + */
> + if (PageTransCompound(page))
> + if (split_huge_page(page) < 0)
> + goto redirty;
> +
> BUG_ON(!PageLocked(page));
> mapping = page->mapping;
> index = page->index;
> _
>
next prev parent reply other threads:[~2020-09-19 4:44 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 4:19 incoming Andrew Morton
2020-09-19 4:20 ` [patch 01/15] mailmap: add older email addresses for Kees Cook Andrew Morton
2020-09-19 4:20 ` [patch 02/15] ksm: reinstate memcg charge on copied pages Andrew Morton
2020-09-19 4:20 ` [patch 03/15] mm: migration of hugetlbfs page skip memcg Andrew Morton
2020-09-19 4:20 ` [patch 04/15] shmem: shmem_writepage() split unlikely i915 THP Andrew Morton
2020-09-19 4:44 ` Matthew Wilcox [this message]
2020-09-19 5:44 ` Hugh Dickins
2020-09-19 16:18 ` Matthew Wilcox
2020-09-20 0:16 ` Hugh Dickins
2020-09-20 3:32 ` Matthew Wilcox
2020-10-02 18:37 ` Matthew Wilcox
2020-10-09 8:14 ` Huang, Ying
2020-10-10 15:32 ` Matthew Wilcox
2020-10-12 2:01 ` Huang, Ying
2020-09-19 4:20 ` [patch 05/15] mm: fix check_move_unevictable_pages() on THP Andrew Morton
2020-09-19 4:20 ` [patch 06/15] mlock: fix unevictable_pgs event counts " Andrew Morton
2020-09-19 4:20 ` [patch 07/15] tmpfs: restore functionality of nr_inodes=0 Andrew Morton
2020-09-19 4:20 ` [patch 08/15] kprobes: fix kill kprobe which has been marked as gone Andrew Morton
2020-09-19 4:20 ` [patch 09/15] mm/thp: fix __split_huge_pmd_locked() for migration PMD Andrew Morton
2020-09-19 4:20 ` [patch 10/15] selftests/vm: fix display of page size in map_hugetlb Andrew Morton
2020-09-19 4:20 ` [patch 11/15] mm/memory_hotplug: drain per-cpu pages again during memory offline Andrew Morton
2020-09-19 4:20 ` [patch 12/15] ftrace: let ftrace_enable_sysctl take a kernel pointer buffer Andrew Morton
2020-09-19 4:20 ` [patch 13/15] stackleak: let stack_erasing_sysctl " Andrew Morton
2020-09-19 4:20 ` [patch 14/15] fs/fs-writeback.c: adjust dirtytime_interval_handler definition to match prototype Andrew Morton
2020-09-19 4:20 ` [patch 15/15] kcsan: kconfig: move to menu 'Generic Kernel Debugging Instruments' Andrew Morton
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