From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, 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: [patch 04/15] shmem: shmem_writepage() split unlikely i915 THP
Date: Fri, 18 Sep 2020 21:20:09 -0700 [thread overview]
Message-ID: <20200919042009.bomzxmrg7%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200918211925.7e97f0ef63d92f5cfe5ccbc5@linux-foundation.org>
From: Hugh Dickins <hughd@google.com>
Subject: shmem: shmem_writepage() split unlikely i915 THP
drivers/gpu/drm/i915/gem/i915_gem_shmem.c contains a shmem_writeback()
which calls shmem_writepage() from a shrinker: that usually works well
enough; but if /sys/kernel/mm/transparent_hugepage/shmem_enabled has been
set to "force" (documented as "Force the huge option on for all - very
useful for testing"), shmem_writepage() is surprised to be called with a
huge page, and crashes on the VM_BUG_ON_PAGE(PageCompound) (I did not find
out where the crash happens when CONFIG_DEBUG_VM is off).
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().
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301401390.5954@eggly.anvils
Fixes: 2d6692e642e7 ("drm/i915: Start writeback from the shrinker")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org> [5.3+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/shmem.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/mm/shmem.c~shmem-shmem_writepage-split-unlikely-i915-thp
+++ a/mm/shmem.c
@@ -1362,7 +1362,15 @@ static int shmem_writepage(struct page *
swp_entry_t swap;
pgoff_t index;
- 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 4:20 UTC|newest]
Thread overview: 29+ 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 ` Andrew Morton [this message]
2020-09-19 4:44 ` [patch 04/15] shmem: shmem_writepage() split unlikely i915 THP Matthew Wilcox
2020-09-19 5:44 ` Hugh Dickins
2020-09-19 5:44 ` Hugh Dickins
2020-09-19 16:18 ` Matthew Wilcox
2020-09-20 0:16 ` Hugh Dickins
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
2020-10-09 8:14 ` Huang, Ying
2020-10-10 15:32 ` Matthew Wilcox
2020-10-12 2:01 ` Huang, Ying
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200919042009.bomzxmrg7%akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=alex.shi@linux.alibaba.com \
--cc=cai@lca.pw \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=mike.kravetz@oracle.com \
--cc=mm-commits@vger.kernel.org \
--cc=shakeelb@google.com \
--cc=shy828301@gmail.com \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.