From: Andrew Morton <akpm@linux-foundation.org>
To: aarcange@redhat.com, akpm@linux-foundation.org,
edumazet@google.com, hughd@google.com,
kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
mike.kravetz@oracle.com, mm-commits@vger.kernel.org,
shy828301@gmail.com, songliubraving@fb.com,
stable@vger.kernel.org, syzkaller@googlegroups.com,
torvalds@linux-foundation.org
Subject: [patch 03/11] khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter()
Date: Thu, 20 Aug 2020 17:42:02 -0700 [thread overview]
Message-ID: <20200821004202.AP6gJKDLE%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200820174132.67fd4a7a9359048f807a533b@linux-foundation.org>
From: Hugh Dickins <hughd@google.com>
Subject: khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter()
syzbot crashes on the VM_BUG_ON_MM(khugepaged_test_exit(mm), mm) in
__khugepaged_enter(): yes, when one thread is about to dump core, has set
core_state, and is waiting for others, another might do something calling
__khugepaged_enter(), which now crashes because I lumped the core_state
test (known as "mmget_still_valid") into khugepaged_test_exit(). I still
think it's best to lump them together, so just in this exceptional case,
check mm->mm_users directly instead of khugepaged_test_exit().
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008141503370.18085@eggly.anvils
Fixes: bbe98f9cadff ("khugepaged: khugepaged_test_exit() check mmget_still_valid()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/khugepaged.c~khugepaged-adjust-vm_bug_on_mm-in-__khugepaged_enter
+++ a/mm/khugepaged.c
@@ -466,7 +466,7 @@ int __khugepaged_enter(struct mm_struct
return -ENOMEM;
/* __khugepaged_exit() must not run from under us */
- VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
+ VM_BUG_ON_MM(atomic_read(&mm->mm_users) == 0, mm);
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
free_mm_slot(mm_slot);
return 0;
_
next prev parent reply other threads:[~2020-08-21 0:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 0:41 incoming Andrew Morton
2020-08-21 0:41 ` [patch 01/11] mailmap: add Andi Kleen Andrew Morton
2020-08-21 0:41 ` [patch 02/11] hugetlb_cgroup: convert comma to semicolon Andrew Morton
2020-08-21 0:42 ` Andrew Morton [this message]
2020-08-21 0:42 ` [patch 04/11] mm/vunmap: add cond_resched() in vunmap_pmd_range Andrew Morton
2020-08-21 0:42 ` [patch 05/11] mm/rodata_test.c: fix missing function declaration Andrew Morton
2020-08-21 0:42 ` [patch 06/11] romfs: fix uninitialized memory leak in romfs_dev_read() Andrew Morton
2020-08-21 0:42 ` [patch 07/11] kernel/relay.c: fix memleak on destroy relay channel Andrew Morton
2020-08-21 0:42 ` [patch 08/11] uprobes: __replace_page() avoid BUG in munlock_vma_page() Andrew Morton
2020-08-21 0:42 ` [patch 09/11] squashfs: avoid bio_alloc() failure with 1Mbyte blocks Andrew Morton
2020-08-21 0:42 ` [patch 10/11] mm: include CMA pages in lowmem_reserve at boot Andrew Morton
2020-08-21 0:42 ` [patch 11/11] mm, page_alloc: fix core hung in free_pcppages_bulk() Andrew Morton
2020-08-21 3:51 ` + fs-binfmt_elf-use-pt_load-p_align-values-for-suitable-start-address-fix.patch added to -mm tree Andrew Morton
2020-08-21 19:57 ` + mm-kmemleak-rely-on-rcu-for-task-stack-scanning.patch " Andrew Morton
2020-08-21 19:58 ` + get_maintainer-exclude-maintainers-files-from-git-fallback.patch " Andrew Morton
2020-08-21 21:33 ` + checkpatch-fix-the-usage-of-capture-group.patch " Andrew Morton
2020-08-21 21:36 ` + mm-gup_benchmark-update-the-documentation-in-kconfig.patch " Andrew Morton
2020-08-21 21:48 ` + mm-madvise-fix-vma-user-after-free.patch " Andrew Morton
2020-08-21 22:34 ` + mm-track-page-table-modifications-in-__apply_to_page_range.patch " Andrew Morton
2020-08-26 1:38 ` + x86-numa-add-nohmat-option-fix.patch " 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=20200821004202.AP6gJKDLE%akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=aarcange@redhat.com \
--cc=edumazet@google.com \
--cc=hughd@google.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=mm-commits@vger.kernel.org \
--cc=shy828301@gmail.com \
--cc=songliubraving@fb.com \
--cc=stable@vger.kernel.org \
--cc=syzkaller@googlegroups.com \
--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.