The quilt patch titled
Subject: mm: fix oops when filemap_map_pmd() without prealloc_pte
has been removed from the -mm tree. Its filename was
mm-fix-oops-when-filemap_map_pmd-without-prealloc_pte.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Hugh Dickins <hughd(a)google.com>
Subject: mm: fix oops when filemap_map_pmd() without prealloc_pte
Date: Fri, 17 Nov 2023 00:49:18 -0800 (PST)
syzbot reports oops in lockdep's __lock_acquire(), called from
__pte_offset_map_lock() called from filemap_map_pages(); or when I run the
repro, the oops comes in pmd_install(), called from filemap_map_pmd()
called from filemap_map_pages(), just before the __pte_offset_map_lock().
The problem is that filemap_map_pmd() has been assuming that when it finds
pmd_none(), a page table has already been prepared in prealloc_pte; and
indeed do_fault_around() has been careful to preallocate one there, when
it finds pmd_none(): but what if *pmd became none in between?
My 6.6 mods in mm/khugepaged.c, avoiding mmap_lock for write, have made it
easy for *pmd to be cleared while servicing a page fault; but even before
those, a huge *pmd might be zapped while a fault is serviced.
The difference in symptomatic stack traces comes from the "memory model"
in use: pmd_install() uses pmd_populate() uses page_to_pfn(): in some
models that is strict, and will oops on the NULL prealloc_pte; in other
models, it will construct a bogus value to be populated into *pmd, then
__pte_offset_map_lock() oops when trying to access split ptlock pointer
(or some other symptom in normal case of ptlock embedded not pointer).
Link: https://lore.kernel.org/linux-mm/20231115065506.19780-1-jose.pekkarinen@fox…
Link: https://lkml.kernel.org/r/6ed0c50c-78ef-0719-b3c5-60c0c010431c@google.com
Fixes: f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths")
Signed-off-by: Hugh Dickins <hughd(a)google.com>
Reported-and-tested-by: syzbot+89edd67979b52675ddec(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-mm/0000000000005e44550608a0806c@google.com/
Reviewed-by: David Hildenbrand <david(a)redhat.com>
Cc: Jann Horn <jannh(a)google.com>,
Cc: Jos�� Pekkarinen <jose.pekkarinen(a)foxhound.fi>
Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org>
Cc: <stable(a)vger.kernel.org> [5.12+]
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/filemap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/filemap.c~mm-fix-oops-when-filemap_map_pmd-without-prealloc_pte
+++ a/mm/filemap.c
@@ -3371,7 +3371,7 @@ static bool filemap_map_pmd(struct vm_fa
}
}
- if (pmd_none(*vmf->pmd))
+ if (pmd_none(*vmf->pmd) && vmf->prealloc_pte)
pmd_install(mm, vmf->pmd, &vmf->prealloc_pte);
return false;
_
Patches currently in -mm which might be from hughd(a)google.com are
The quilt patch titled
Subject: hugetlb: fix null-ptr-deref in hugetlb_vma_lock_write
has been removed from the -mm tree. Its filename was
hugetlb-fix-null-ptr-deref-in-hugetlb_vma_lock_write.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Mike Kravetz <mike.kravetz(a)oracle.com>
Subject: hugetlb: fix null-ptr-deref in hugetlb_vma_lock_write
Date: Mon, 13 Nov 2023 17:20:33 -0800
The routine __vma_private_lock tests for the existence of a reserve map
associated with a private hugetlb mapping. A pointer to the reserve map
is in vma->vm_private_data. __vma_private_lock was checking the pointer
for NULL. However, it is possible that the low bits of the pointer could
be used as flags. In such instances, vm_private_data is not NULL and not
a valid pointer. This results in the null-ptr-deref reported by syzbot:
general protection fault, probably for non-canonical address 0xdffffc000000001d:
0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]
CPU: 0 PID: 5048 Comm: syz-executor139 Not tainted 6.6.0-rc7-syzkaller-00142-g88
8cf78c29e2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 1
0/09/2023
RIP: 0010:__lock_acquire+0x109/0x5de0 kernel/locking/lockdep.c:5004
...
Call Trace:
<TASK>
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
down_write+0x93/0x200 kernel/locking/rwsem.c:1573
hugetlb_vma_lock_write mm/hugetlb.c:300 [inline]
hugetlb_vma_lock_write+0xae/0x100 mm/hugetlb.c:291
__hugetlb_zap_begin+0x1e9/0x2b0 mm/hugetlb.c:5447
hugetlb_zap_begin include/linux/hugetlb.h:258 [inline]
unmap_vmas+0x2f4/0x470 mm/memory.c:1733
exit_mmap+0x1ad/0xa60 mm/mmap.c:3230
__mmput+0x12a/0x4d0 kernel/fork.c:1349
mmput+0x62/0x70 kernel/fork.c:1371
exit_mm kernel/exit.c:567 [inline]
do_exit+0x9ad/0x2a20 kernel/exit.c:861
__do_sys_exit kernel/exit.c:991 [inline]
__se_sys_exit kernel/exit.c:989 [inline]
__x64_sys_exit+0x42/0x50 kernel/exit.c:989
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Mask off low bit flags before checking for NULL pointer. In addition, the
reserve map only 'belongs' to the OWNER (parent in parent/child
relationships) so also check for the OWNER flag.
Link: https://lkml.kernel.org/r/20231114012033.259600-1-mike.kravetz@oracle.com
Reported-by: syzbot+6ada951e7c0f7bc8a71e(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-mm/00000000000078d1e00608d7878b@google.com/
Fixes: bf4916922c60 ("hugetlbfs: extend hugetlb_vma_lock to private VMAs")
Signed-off-by: Mike Kravetz <mike.kravetz(a)oracle.com>
Reviewed-by: Rik van Riel <riel(a)surriel.com>
Cc: Edward Adam Davis <eadavis(a)qq.com>
Cc: Muchun Song <muchun.song(a)linux.dev>
Cc: Nathan Chancellor <nathan(a)kernel.org>
Cc: Nick Desaulniers <ndesaulniers(a)google.com>
Cc: Tom Rix <trix(a)redhat.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
include/linux/hugetlb.h | 5 +----
mm/hugetlb.c | 7 +++++++
2 files changed, 8 insertions(+), 4 deletions(-)
--- a/include/linux/hugetlb.h~hugetlb-fix-null-ptr-deref-in-hugetlb_vma_lock_write
+++ a/include/linux/hugetlb.h
@@ -1268,10 +1268,7 @@ static inline bool __vma_shareable_lock(
return (vma->vm_flags & VM_MAYSHARE) && vma->vm_private_data;
}
-static inline bool __vma_private_lock(struct vm_area_struct *vma)
-{
- return (!(vma->vm_flags & VM_MAYSHARE)) && vma->vm_private_data;
-}
+bool __vma_private_lock(struct vm_area_struct *vma);
/*
* Safe version of huge_pte_offset() to check the locks. See comments
--- a/mm/hugetlb.c~hugetlb-fix-null-ptr-deref-in-hugetlb_vma_lock_write
+++ a/mm/hugetlb.c
@@ -1182,6 +1182,13 @@ static int is_vma_resv_set(struct vm_are
return (get_vma_private_data(vma) & flag) != 0;
}
+bool __vma_private_lock(struct vm_area_struct *vma)
+{
+ return !(vma->vm_flags & VM_MAYSHARE) &&
+ get_vma_private_data(vma) & ~HPAGE_RESV_MASK &&
+ is_vma_resv_set(vma, HPAGE_RESV_OWNER);
+}
+
void hugetlb_dup_vma_private(struct vm_area_struct *vma)
{
VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
_
Patches currently in -mm which might be from mike.kravetz(a)oracle.com are
The kernel hangs for a good 12 seconds without any info being printed to
dmesg, very early in the boot process, if this regulator is not enabled.
Force-enable it to work around this issue, until we know more about the
underlying problem.
Signed-off-by: Paul Cercueil <paul(a)crapouillou.net>
Fixes: 8620cc2f99b7 ("ARM: dts: exynos: Add devicetree file for the Galaxy S2")
Cc: <stable(a)vger.kernel.org> # v5.8+
---
arch/arm/boot/dts/samsung/exynos4210-i9100.dts | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm/boot/dts/samsung/exynos4210-i9100.dts b/arch/arm/boot/dts/samsung/exynos4210-i9100.dts
index a9ec1f6c1dea..a076a1dfe41f 100644
--- a/arch/arm/boot/dts/samsung/exynos4210-i9100.dts
+++ b/arch/arm/boot/dts/samsung/exynos4210-i9100.dts
@@ -527,6 +527,14 @@ vtcam_reg: LDO12 {
regulator-name = "VT_CAM_1.8V";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
+
+ /*
+ * Force-enable this regulator; otherwise the
+ * kernel hangs very early in the boot process
+ * for about 12 seconds, without apparent
+ * reason.
+ */
+ regulator-always-on;
};
vcclcd_reg: LDO13 {
--
2.42.0