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commit 55d134a7b499c77e7cfd0ee41046f3c376e791e5 upstream.
The hugetlb_cma code passes 0 in the order_per_bit argument to
cma_declare_contiguous_nid (the alignment, computed using the page order,
is correctly passed in).
This causes a bit in the cma allocation bitmap to always represent a 4k
page, making the bitmaps potentially very large, and slower.
It would create bitmaps that would be pretty big. E.g. for a 4k page
size on x86, hugetlb_cma=64G would mean a bitmap size of (64G / 4k) / 8
== 2M. With HUGETLB_PAGE_ORDER as order_per_bit, as intended, this
would be (64G / 2M) / 8 == 4k. So, that's quite a difference.
Also, this restricted the hugetlb_cma area to ((PAGE_SIZE <<
MAX_PAGE_ORDER) * 8) * PAGE_SIZE (e.g. 128G on x86) , since
bitmap_alloc uses normal page allocation, and is thus restricted by
MAX_PAGE_ORDER. Specifying anything about that would fail the CMA
initialization.
So, correctly pass in the order instead.
Link: https://lkml.kernel.org/r/20240404162515.527802-2-fvdl@google.com
Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Frank van der Linden <fvdl@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 52ccdde16b6540abe43b6f8d8e1e1ec90b0983af upstream.
When I did memory failure tests recently, below warning occurs:
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 8 PID: 1011 at kernel/locking/lockdep.c:232 __lock_acquire+0xccb/0x1ca0
Modules linked in: mce_inject hwpoison_inject
CPU: 8 PID: 1011 Comm: bash Kdump: loaded Not tainted 6.9.0-rc3-next-20240410-00012-gdb69f219f4be #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
RIP: 0010:__lock_acquire+0xccb/0x1ca0
RSP: 0018:ffffa7a1c7fe3bd0 EFLAGS: 00000082
RAX: 0000000000000000 RBX: eb851eb853975fcf RCX: ffffa1ce5fc1c9c8
RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffffa1ce5fc1c9c0
RBP: ffffa1c6865d3280 R08: ffffffffb0f570a8 R09: 0000000000009ffb
R10: 0000000000000286 R11: ffffffffb0f2ad50 R12: ffffa1c6865d3d10
R13: ffffa1c6865d3c70 R14: 0000000000000000 R15: 0000000000000004
FS: 00007ff9f32aa740(0000) GS:ffffa1ce5fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff9f3134ba0 CR3: 00000008484e4000 CR4: 00000000000006f0
Call Trace:
<TASK>
lock_acquire+0xbe/0x2d0
_raw_spin_lock_irqsave+0x3a/0x60
hugepage_subpool_put_pages.part.0+0xe/0xc0
free_huge_folio+0x253/0x3f0
dissolve_free_huge_page+0x147/0x210
__page_handle_poison+0x9/0x70
memory_failure+0x4e6/0x8c0
hard_offline_page_store+0x55/0xa0
kernfs_fop_write_iter+0x12c/0x1d0
vfs_write+0x380/0x540
ksys_write+0x64/0xe0
do_syscall_64+0xbc/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9f3114887
RSP: 002b:00007ffecbacb458 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007ff9f3114887
RDX: 000000000000000c RSI: 0000564494164e10 RDI: 0000000000000001
RBP: 0000564494164e10 R08: 00007ff9f31d1460 R09: 000000007fffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c
R13: 00007ff9f321b780 R14: 00007ff9f3217600 R15: 00007ff9f3216a00
</TASK>
Kernel panic - not syncing: kernel: panic_on_warn set ...
CPU: 8 PID: 1011 Comm: bash Kdump: loaded Not tainted 6.9.0-rc3-next-20240410-00012-gdb69f219f4be #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
panic+0x326/0x350
check_panic_on_warn+0x4f/0x50
__warn+0x98/0x190
report_bug+0x18e/0x1a0
handle_bug+0x3d/0x70
exc_invalid_op+0x18/0x70
asm_exc_invalid_op+0x1a/0x20
RIP: 0010:__lock_acquire+0xccb/0x1ca0
RSP: 0018:ffffa7a1c7fe3bd0 EFLAGS: 00000082
RAX: 0000000000000000 RBX: eb851eb853975fcf RCX: ffffa1ce5fc1c9c8
RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffffa1ce5fc1c9c0
RBP: ffffa1c6865d3280 R08: ffffffffb0f570a8 R09: 0000000000009ffb
R10: 0000000000000286 R11: ffffffffb0f2ad50 R12: ffffa1c6865d3d10
R13: ffffa1c6865d3c70 R14: 0000000000000000 R15: 0000000000000004
lock_acquire+0xbe/0x2d0
_raw_spin_lock_irqsave+0x3a/0x60
hugepage_subpool_put_pages.part.0+0xe/0xc0
free_huge_folio+0x253/0x3f0
dissolve_free_huge_page+0x147/0x210
__page_handle_poison+0x9/0x70
memory_failure+0x4e6/0x8c0
hard_offline_page_store+0x55/0xa0
kernfs_fop_write_iter+0x12c/0x1d0
vfs_write+0x380/0x540
ksys_write+0x64/0xe0
do_syscall_64+0xbc/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9f3114887
RSP: 002b:00007ffecbacb458 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007ff9f3114887
RDX: 000000000000000c RSI: 0000564494164e10 RDI: 0000000000000001
RBP: 0000564494164e10 R08: 00007ff9f31d1460 R09: 000000007fffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c
R13: 00007ff9f321b780 R14: 00007ff9f3217600 R15: 00007ff9f3216a00
</TASK>
After git bisecting and digging into the code, I believe the root cause is
that _deferred_list field of folio is unioned with _hugetlb_subpool field.
In __update_and_free_hugetlb_folio(), folio->_deferred_list is
initialized leading to corrupted folio->_hugetlb_subpool when folio is
hugetlb. Later free_huge_folio() will use _hugetlb_subpool and above
warning happens.
But it is assumed hugetlb flag must have been cleared when calling
folio_put() in update_and_free_hugetlb_folio(). This assumption is broken
due to below race:
CPU1 CPU2
dissolve_free_huge_page update_and_free_pages_bulk
update_and_free_hugetlb_folio hugetlb_vmemmap_restore_folios
folio_clear_hugetlb_vmemmap_optimized
clear_flag = folio_test_hugetlb_vmemmap_optimized
if (clear_flag) <-- False, it's already cleared.
__folio_clear_hugetlb(folio) <-- Hugetlb is not cleared.
folio_put
free_huge_folio <-- free_the_page is expected.
list_for_each_entry()
__folio_clear_hugetlb <-- Too late.
Fix this issue by checking whether folio is hugetlb directly instead of
checking clear_flag to close the race window.
Link: https://lkml.kernel.org/r/20240419085819.1901645-1-linmiaohe@huawei.com
Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit b76b46902c2d0395488c8412e1116c2486cdfcb2 ]
There is a recent report on UFFDIO_COPY over hugetlb:
https://lore.kernel.org/all/000000000000ee06de0616177560@google.com/
350: lockdep_assert_held(&hugetlb_lock);
Should be an issue in hugetlb but triggered in an userfault context, where
it goes into the unlikely path where two threads modifying the resv map
together. Mike has a fix in that path for resv uncharge but it looks like
the locking criteria was overlooked: hugetlb_cgroup_uncharge_folio_rsvd()
will update the cgroup pointer, so it requires to be called with the lock
held.
Link: https://lkml.kernel.org/r/20240417211836.2742593-3-peterx@redhat.com
Fixes: 79aa925bf239 ("hugetlb_cgroup: fix reservation accounting")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: syzbot+4b8077a5fccc61c385a1@syzkaller.appspotmail.com
Reviewed-by: Mina Almasry <almasrymina@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d4ab0316cc33aeedf6dcb1c2c25e097a25766132 ]
Continue to use a folio inside free_huge_page() by converting
hugetlb_cgroup_uncharge_page*() to folios.
Link: https://lkml.kernel.org/r/20221101223059.460937-8-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Bui Quang Minh <minhquangbui99@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: b76b46902c2d ("mm/hugetlb: fix missing hugetlb_lock for resv uncharge")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 0356c4b96f6890dd61af4c902f681764f4bdba09 ]
Use folios inside free_huge_page(), this is in preparation for converting
hugetlb_cgroup_uncharge_page() to take in a folio.
Link: https://lkml.kernel.org/r/20221101223059.460937-7-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Bui Quang Minh <minhquangbui99@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: b76b46902c2d ("mm/hugetlb: fix missing hugetlb_lock for resv uncharge")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f074732d599e19a2a5b12e54743ad5eaccbe6550 ]
Introduce folios in __remove_hugetlb_page() by converting
hugetlb_cgroup_from_page() to use folios.
Also gets rid of unsed hugetlb_cgroup_from_page_resv() function.
Link: https://lkml.kernel.org/r/20221101223059.460937-3-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Bui Quang Minh <minhquangbui99@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: b76b46902c2d ("mm/hugetlb: fix missing hugetlb_lock for resv uncharge")
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 187da0f8250aa94bd96266096aef6f694e0b4cd2 upstream.
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@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@oracle.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Cc: Edward Adam Davis <eadavis@qq.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit bf4916922c60f43efaa329744b3eef539aa6a2b2 upstream.
Extend the locking scheme used to protect shared hugetlb mappings from
truncate vs page fault races, in order to protect private hugetlb mappings
(with resv_map) against MADV_DONTNEED.
Add a read-write semaphore to the resv_map data structure, and use that
from the hugetlb_vma_(un)lock_* functions, in preparation for closing the
race between MADV_DONTNEED and page faults.
Link: https://lkml.kernel.org/r/20231006040020.3677377-3-riel@surriel.com
Fixes: 04ada095dcfc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing")
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 92fe9dcbe4e109a7ce6bab3e452210a35b0ab493 upstream.
Patch series "hugetlbfs: close race between MADV_DONTNEED and page fault", v7.
Malloc libraries, like jemalloc and tcalloc, take decisions on when to
call madvise independently from the code in the main application.
This sometimes results in the application page faulting on an address,
right after the malloc library has shot down the backing memory with
MADV_DONTNEED.
Usually this is harmless, because we always have some 4kB pages sitting
around to satisfy a page fault. However, with hugetlbfs systems often
allocate only the exact number of huge pages that the application wants.
Due to TLB batching, hugetlbfs MADV_DONTNEED will free pages outside of
any lock taken on the page fault path, which can open up the following
race condition:
CPU 1 CPU 2
MADV_DONTNEED
unmap page
shoot down TLB entry
page fault
fail to allocate a huge page
killed with SIGBUS
free page
Fix that race by extending the hugetlb_vma_lock locking scheme to also
cover private hugetlb mappings (with resv_map), and pulling the locking
from __unmap_hugepage_final_range into helper functions called from
zap_page_range_single. This ensures page faults stay locked out of the
MADV_DONTNEED VMA until the huge pages have actually been freed.
This patch (of 3):
Hugetlbfs leaves a dangling pointer in the VMA if mmap fails. This has
not been a problem so far, but other code in this patch series tries to
follow that pointer.
Link: https://lkml.kernel.org/r/20231006040020.3677377-1-riel@surriel.com
Link: https://lkml.kernel.org/r/20231006040020.3677377-2-riel@surriel.com
Fixes: 04ada095dcfc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Rik van Riel <riel@surriel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 32c877191e022b55fe3a374f3d7e9fb5741c514d upstream.
Patch series "Fix hugetlb free path race with memory errors".
In the discussion of Jiaqi Yan's series "Improve hugetlbfs read on
HWPOISON hugepages" the race window was discovered.
https://lore.kernel.org/linux-mm/20230616233447.GB7371@monkey/
Freeing a hugetlb page back to low level memory allocators is performed
in two steps.
1) Under hugetlb lock, remove page from hugetlb lists and clear destructor
2) Outside lock, allocate vmemmap if necessary and call low level free
Between these two steps, the hugetlb page will appear as a normal
compound page. However, vmemmap for tail pages could be missing.
If a memory error occurs at this time, we could try to update page
flags non-existant page structs.
A much more detailed description is in the first patch.
The first patch addresses the race window. However, it adds a
hugetlb_lock lock/unlock cycle to every vmemmap optimized hugetlb page
free operation. This could lead to slowdowns if one is freeing a large
number of hugetlb pages.
The second path optimizes the update_and_free_pages_bulk routine to only
take the lock once in bulk operations.
The second patch is technically not a bug fix, but includes a Fixes tag
and Cc stable to avoid a performance regression. It can be combined with
the first, but was done separately make reviewing easier.
This patch (of 2):
Freeing a hugetlb page and releasing base pages back to the underlying
allocator such as buddy or cma is performed in two steps:
- remove_hugetlb_folio() is called to remove the folio from hugetlb
lists, get a ref on the page and remove hugetlb destructor. This
all must be done under the hugetlb lock. After this call, the page
can be treated as a normal compound page or a collection of base
size pages.
- update_and_free_hugetlb_folio() is called to allocate vmemmap if
needed and the free routine of the underlying allocator is called
on the resulting page. We can not hold the hugetlb lock here.
One issue with this scheme is that a memory error could occur between
these two steps. In this case, the memory error handling code treats
the old hugetlb page as a normal compound page or collection of base
pages. It will then try to SetPageHWPoison(page) on the page with an
error. If the page with error is a tail page without vmemmap, a write
error will occur when trying to set the flag.
Address this issue by modifying remove_hugetlb_folio() and
update_and_free_hugetlb_folio() such that the hugetlb destructor is not
cleared until after allocating vmemmap. Since clearing the destructor
requires holding the hugetlb lock, the clearing is done in
remove_hugetlb_folio() if the vmemmap is present. This saves a
lock/unlock cycle. Otherwise, destructor is cleared in
update_and_free_hugetlb_folio() after allocating vmemmap.
Note that this will leave hugetlb pages in a state where they are marked
free (by hugetlb specific page flag) and have a ref count. This is not
a normal state. The only code that would notice is the memory error
code, and it is set up to retry in such a case.
A subsequent patch will create a routine to do bulk processing of
vmemmap allocation. This will eliminate a lock/unlock cycle for each
hugetlb page in the case where we are freeing a large number of pages.
Link: https://lkml.kernel.org/r/20230711220942.43706-1-mike.kravetz@oracle.com
Link: https://lkml.kernel.org/r/20230711220942.43706-2-mike.kravetz@oracle.com
Fixes: ad2fa3717b74 ("mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Tested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 60d5b473d61be61ac315e544fcd6a8234a79500e upstream.
This patch fixes an issue that a hugetlb uffd-wr-protected mapping can be
writable even with uffd-wp bit set. It only happens with hugetlb private
mappings, when someone firstly wr-protects a missing pte (which will
install a pte marker), then a write to the same page without any prior
access to the page.
Userfaultfd-wp trap for hugetlb was implemented in hugetlb_fault() before
reaching hugetlb_wp() to avoid taking more locks that userfault won't
need. However there's one CoW optimization path that can trigger
hugetlb_wp() inside hugetlb_no_page(), which will bypass the trap.
This patch skips hugetlb_wp() for CoW and retries the fault if uffd-wp bit
is detected. The new path will only trigger in the CoW optimization path
because generic hugetlb_fault() (e.g. when a present pte was
wr-protected) will resolve the uffd-wp bit already. Also make sure
anonymous UNSHARE won't be affected and can still be resolved, IOW only
skip CoW not CoR.
This patch will be needed for v5.19+ hence copy stable.
[peterx@redhat.com: v2]
Link: https://lkml.kernel.org/r/ZBzOqwF2wrHgBVZb@x1n
[peterx@redhat.com: v3]
Link: https://lkml.kernel.org/r/20230324142620.2344140-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20230321191840.1897940-1-peterx@redhat.com
Fixes: 166f3ecc0daf ("mm/hugetlb: hook page faults for uffd write protection")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit fed15f1345dc8a7fc8baa81e8b55c3ba010d7f4b upstream.
Userfaultfd-wp uses pte markers to mark wr-protected pages for both shmem
and hugetlb. Shmem has pre-allocation ready for markers, but hugetlb path
was overlooked.
Doing so by calling huge_pte_alloc() if the initial pgtable walk fails to
find the huge ptep. It's possible that huge_pte_alloc() can fail with
high memory pressure, in that case stop the loop immediately and fail
silently. This is not the most ideal solution but it matches with what we
do with shmem meanwhile it avoids the splat in dmesg.
Link: https://lkml.kernel.org/r/20230104225207.1066932-2-peterx@redhat.com
Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: James Houghton <jthoughton@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: <stable@vger.kernel.org> [5.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
hugetlb_change_protection()
commit 44f86392bdd165da7e43d3c772aeb1e128ffd6c8 upstream.
We have to update the uffd-wp SWP PTE bit independent of the type of
migration entry. Currently, if we're unlucky and we want to install/clear
the uffd-wp bit just while we're migrating a read-only mapped hugetlb
page, we would miss to set/clear the uffd-wp bit.
Further, if we're processing a readable-exclusive migration entry and
neither want to set or clear the uffd-wp bit, we could currently end up
losing the uffd-wp bit. Note that the same would hold for writable
migrating entries, however, having a writable migration entry with the
uffd-wp bit set would already mean that something went wrong.
Note that the change from !is_readable_migration_entry ->
writable_migration_entry is harmless and actually cleaner, as raised by
Miaohe Lin and discussed in [1].
[1] https://lkml.kernel.org/r/90dd6a93-4500-e0de-2bf0-bf522c311b0c@huawei.com
Link: https://lkml.kernel.org/r/20221222205511.675832-3-david@redhat.com
Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 0e678153f5be7e6c8d28835f5a678618da4b7a9c upstream.
Patch series "mm/hugetlb: uffd-wp fixes for hugetlb_change_protection()".
Playing with virtio-mem and background snapshots (using uffd-wp) on
hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the
details, hugetlb_change_protection() seems to not handle uffd-wp correctly
in all cases.
Patch #1 fixes my test case. I don't have reproducers for patch #2, as it
requires running into migration entries.
I did not yet check in detail yet if !hugetlb code requires similar care.
This patch (of 2):
There are two problematic cases when stumbling over a PTE marker in
hugetlb_change_protection():
(1) We protect an uffd-wp PTE marker a second time using uffd-wp: we will
end up in the "!huge_pte_none(pte)" case and mess up the PTE marker.
(2) We unprotect a uffd-wp PTE marker: we will similarly end up in the
"!huge_pte_none(pte)" case even though we cleared the PTE, because
the "pte" variable is stale. We'll mess up the PTE marker.
For example, if we later stumble over such a "wrongly modified" PTE marker,
we'll treat it like a present PTE that maps some garbage page.
This can, for example, be triggered by mapping a memfd backed by huge
pages, registering uffd-wp, uffd-wp'ing an unmapped page and (a)
uffd-wp'ing it a second time; or (b) uffd-unprotecting it; or (c)
unregistering uffd-wp. Then, ff we trigger fallocate(FALLOC_FL_PUNCH_HOLE)
on that file range, we will run into a VM_BUG_ON:
[ 195.039560] page:00000000ba1f2987 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0
[ 195.039565] flags: 0x7ffffc0001000(reserved|node=0|zone=0|lastcpupid=0x1fffff)
[ 195.039568] raw: 0007ffffc0001000 ffffe742c0000008 ffffe742c0000008 0000000000000000
[ 195.039569] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
[ 195.039569] page dumped because: VM_BUG_ON_PAGE(compound && !PageHead(page))
[ 195.039573] ------------[ cut here ]------------
[ 195.039574] kernel BUG at mm/rmap.c:1346!
[ 195.039579] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 195.039581] CPU: 7 PID: 4777 Comm: qemu-system-x86 Not tainted 6.0.12-200.fc36.x86_64 #1
[ 195.039583] Hardware name: LENOVO 20WNS1F81N/20WNS1F81N, BIOS N35ET50W (1.50 ) 09/15/2022
[ 195.039584] RIP: 0010:page_remove_rmap+0x45b/0x550
[ 195.039588] Code: [...]
[ 195.039589] RSP: 0018:ffffbc03c3633ba8 EFLAGS: 00010292
[ 195.039591] RAX: 0000000000000040 RBX: ffffe742c0000000 RCX: 0000000000000000
[ 195.039592] RDX: 0000000000000002 RSI: ffffffff8e7aac1a RDI: 00000000ffffffff
[ 195.039592] RBP: 0000000000000001 R08: 0000000000000000 R09: ffffbc03c3633a08
[ 195.039593] R10: 0000000000000003 R11: ffffffff8f146328 R12: ffff9b04c42754b0
[ 195.039594] R13: ffffffff8fcc6328 R14: ffffbc03c3633c80 R15: ffff9b0484ab9100
[ 195.039595] FS: 00007fc7aaf68640(0000) GS:ffff9b0bbf7c0000(0000) knlGS:0000000000000000
[ 195.039596] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 195.039597] CR2: 000055d402c49110 CR3: 0000000159392003 CR4: 0000000000772ee0
[ 195.039598] PKRU: 55555554
[ 195.039599] Call Trace:
[ 195.039600] <TASK>
[ 195.039602] __unmap_hugepage_range+0x33b/0x7d0
[ 195.039605] unmap_hugepage_range+0x55/0x70
[ 195.039608] hugetlb_vmdelete_list+0x77/0xa0
[ 195.039611] hugetlbfs_fallocate+0x410/0x550
[ 195.039612] ? _raw_spin_unlock_irqrestore+0x23/0x40
[ 195.039616] vfs_fallocate+0x12e/0x360
[ 195.039618] __x64_sys_fallocate+0x40/0x70
[ 195.039620] do_syscall_64+0x58/0x80
[ 195.039623] ? syscall_exit_to_user_mode+0x17/0x40
[ 195.039624] ? do_syscall_64+0x67/0x80
[ 195.039626] entry_SYSCALL_64_after_hwframe+0x63/0xcd
[ 195.039628] RIP: 0033:0x7fc7b590651f
[ 195.039653] Code: [...]
[ 195.039654] RSP: 002b:00007fc7aaf66e70 EFLAGS: 00000293 ORIG_RAX: 000000000000011d
[ 195.039655] RAX: ffffffffffffffda RBX: 0000558ef4b7f370 RCX: 00007fc7b590651f
[ 195.039656] RDX: 0000000018000000 RSI: 0000000000000003 RDI: 000000000000000c
[ 195.039657] RBP: 0000000008000000 R08: 0000000000000000 R09: 0000000000000073
[ 195.039658] R10: 0000000008000000 R11: 0000000000000293 R12: 0000000018000000
[ 195.039658] R13: 00007fb8bbe00000 R14: 000000000000000c R15: 0000000000001000
[ 195.039661] </TASK>
Fix it by not going into the "!huge_pte_none(pte)" case if we stumble over
an exclusive marker. spin_unlock() + continue would get the job done.
However, instead, make it clearer that there are no fall-through
statements: we process each case (hwpoison, migration, marker, !none,
none) and then unlock the page table to continue with the next PTE. Let's
avoid "continue" statements and use a single spin_unlock() at the end.
Link: https://lkml.kernel.org/r/20221222205511.675832-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221222205511.675832-2-david@redhat.com
Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit b30c14cd61025eeea2f2e8569606cd167ba9ad2d upstream.
PMD sharing can only be done in PUD_SIZE-aligned pieces of VMAs; however,
it is possible that HugeTLB VMAs are split without unsharing the PMDs
first.
Without this fix, it is possible to hit the uffd-wp-related WARN_ON_ONCE
in hugetlb_change_protection [1]. The key there is that
hugetlb_unshare_all_pmds will not attempt to unshare PMDs in
non-PUD_SIZE-aligned sections of the VMA.
It might seem ideal to unshare in hugetlb_vm_op_open, but we need to
unshare in both the new and old VMAs, so unsharing in hugetlb_vm_op_split
seems natural.
[1]: https://lore.kernel.org/linux-mm/CADrL8HVeOkj0QH5VZZbRzybNE8CG-tEGFshnA+bG9nMgcWtBSg@mail.gmail.com/
Link: https://lkml.kernel.org/r/20230104231910.1464197-1-jthoughton@google.com
Fixes: 6dfeaff93be1 ("hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp")
Signed-off-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit e700898fa075c69b3ae02b702ab57fb75e1a82ec upstream.
Commit bbff39cc6cbc ("hugetlb: allocate vma lock for all sharable vmas")
removed the pmd sharable checks in the vma lock helper routines. However,
it left the functional version of helper routines behind #ifdef
CONFIG_ARCH_WANT_HUGE_PMD_SHARE. Therefore, the vma lock is not being
used for sharable vmas on architectures that do not support pmd sharing.
On these architectures, a potential fault/truncation race is exposed that
could leave pages in a hugetlb file past i_size until the file is removed.
Move the functional vma lock helpers outside the ifdef, and remove the
non-functional stubs. Since the vma lock is not just for pmd sharing,
rename the routine __vma_shareable_flags_pmd.
Link: https://lkml.kernel.org/r/20221212235042.178355-1-mike.kravetz@oracle.com
Fixes: bbff39cc6cbc ("hugetlb: allocate vma lock for all sharable vmas")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
madvise(MADV_DONTNEED) ends up calling zap_page_range() to clear page
tables associated with the address range. For hugetlb vmas,
zap_page_range will call __unmap_hugepage_range_final. However,
__unmap_hugepage_range_final assumes the passed vma is about to be removed
and deletes the vma_lock to prevent pmd sharing as the vma is on the way
out. In the case of madvise(MADV_DONTNEED) the vma remains, but the
missing vma_lock prevents pmd sharing and could potentially lead to issues
with truncation/fault races.
This issue was originally reported here [1] as a BUG triggered in
page_try_dup_anon_rmap. Prior to the introduction of the hugetlb
vma_lock, __unmap_hugepage_range_final cleared the VM_MAYSHARE flag to
prevent pmd sharing. Subsequent faults on this vma were confused as
VM_MAYSHARE indicates a sharable vma, but was not set so page_mapping was
not set in new pages added to the page table. This resulted in pages that
appeared anonymous in a VM_SHARED vma and triggered the BUG.
Address issue by adding a new zap flag ZAP_FLAG_UNMAP to indicate an unmap
call from unmap_vmas(). This is used to indicate the 'final' unmapping of
a hugetlb vma. When called via MADV_DONTNEED, this flag is not set and
the vm_lock is not deleted.
[1] https://lore.kernel.org/lkml/CAO4mrfdLMXsao9RF4fUE8-Wfde8xmjsKrTNMNC9wjUb6JudD0g@mail.gmail.com/
Link: https://lkml.kernel.org/r/20221114235507.294320-3-mike.kravetz@oracle.com
Fixes: 90e7e7f5ef3f ("mm: enable MADV_DONTNEED for hugetlb mappings")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Wei Chen <harperchen1110@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Commit 2b21624fc232 ("hugetlb: freeze allocated pages before creating
hugetlb pages") changed the order page flags were cleared and set in the
head page. It moved the __ClearPageReserved after __SetPageHead.
However, there is a check to make sure __ClearPageReserved is never done
on a head page. If CONFIG_DEBUG_VM_PGFLAGS is enabled, the following BUG
will be hit when creating a hugetlb gigantic page:
page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
------------[ cut here ]------------
kernel BUG at include/linux/page-flags.h:500!
Call Trace will differ depending on whether hugetlb page is created
at boot time or run time.
Make sure to __ClearPageReserved BEFORE __SetPageHead.
Link: https://lkml.kernel.org/r/20221118195249.178319-1-mike.kravetz@oracle.com
Fixes: 2b21624fc232 ("hugetlb: freeze allocated pages before creating hugetlb pages")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Tested-by: Tarun Sahu <tsahu@linux.ibm.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This change is very similar to the change that was made for shmem [1], and
it solves the same problem but for HugeTLBFS instead.
Currently, when poison is found in a HugeTLB page, the page is removed
from the page cache. That means that attempting to map or read that
hugepage in the future will result in a new hugepage being allocated
instead of notifying the user that the page was poisoned. As [1] states,
this is effectively memory corruption.
The fix is to leave the page in the page cache. If the user attempts to
use a poisoned HugeTLB page with a syscall, the syscall will fail with
EIO, the same error code that shmem uses. For attempts to map the page,
the thread will get a BUS_MCEERR_AR SIGBUS.
[1]: commit a76054266661 ("mm: shmem: don't truncate page if memory failure happens")
Link: https://lkml.kernel.org/r/20221018200125.848471-1-jthoughton@google.com
Signed-off-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Tested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The hugetlb vma_lock structure hangs off the vm_private_data pointer of
sharable hugetlb vmas. The structure is vma specific and can not be
shared between vmas. At fork and various other times, vmas are duplicated
via vm_area_dup(). When this happens, the pointer in the newly created
vma must be cleared and the structure reallocated. Two hugetlb specific
routines deal with this hugetlb_dup_vma_private and hugetlb_vm_op_open.
Both routines are called for newly created vmas. hugetlb_dup_vma_private
would always clear the pointer and hugetlb_vm_op_open would allocate the
new vms_lock structure. This did not work in the case of this calling
sequence pointed out in [1].
move_vma
copy_vma
new_vma = vm_area_dup(vma);
new_vma->vm_ops->open(new_vma); --> new_vma has its own vma lock.
is_vm_hugetlb_page(vma)
clear_vma_resv_huge_pages
hugetlb_dup_vma_private --> vma->vm_private_data is set to NULL
When clearing hugetlb_dup_vma_private we actually leak the associated
vma_lock structure.
The vma_lock structure contains a pointer to the associated vma. This
information can be used in hugetlb_dup_vma_private and hugetlb_vm_op_open
to ensure we only clear the vm_private_data of newly created (copied)
vmas. In such cases, the vma->vma_lock->vma field will not point to the
vma.
Update hugetlb_dup_vma_private and hugetlb_vm_op_open to not clear
vm_private_data if vma->vma_lock->vma == vma. Also, log a warning if
hugetlb_vm_op_open ever encounters the case where vma_lock has already
been correctly allocated for the vma.
[1] https://lore.kernel.org/linux-mm/5154292a-4c55-28cd-0935-82441e512fc3@huawei.com/
Link: https://lkml.kernel.org/r/20221019201957.34607-1-mike.kravetz@oracle.com
Fixes: 131a79b474e9 ("hugetlb: fix vma lock handling during split vma and range unmapping")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Prakash Sangappa <prakash.sangappa@oracle.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The h->*_huge_pages counters are protected by the hugetlb_lock, but
alloc_huge_page has a corner case where it can decrement the counter
outside of the lock.
This could lead to a corrupted value of h->resv_huge_pages, which we have
observed on our systems.
Take the hugetlb_lock before decrementing h->resv_huge_pages to avoid a
potential race.
Link: https://lkml.kernel.org/r/20221017202505.0e6a4fcd@imladris.surriel.com
Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count")
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Glen McCready <gkmccready@meta.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull more MM updates from Andrew Morton:
- fix a race which causes page refcounting errors in ZONE_DEVICE pages
(Alistair Popple)
- fix userfaultfd test harness instability (Peter Xu)
- various other patches in MM, mainly fixes
* tag 'mm-stable-2022-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (29 commits)
highmem: fix kmap_to_page() for kmap_local_page() addresses
mm/page_alloc: fix incorrect PGFREE and PGALLOC for high-order page
mm/selftest: uffd: explain the write missing fault check
mm/hugetlb: use hugetlb_pte_stable in migration race check
mm/hugetlb: fix race condition of uffd missing/minor handling
zram: always expose rw_page
LoongArch: update local TLB if PTE entry exists
mm: use update_mmu_tlb() on the second thread
kasan: fix array-bounds warnings in tests
hmm-tests: add test for migrate_device_range()
nouveau/dmem: evict device private memory during release
nouveau/dmem: refactor nouveau_dmem_fault_copy_one()
mm/migrate_device.c: add migrate_device_range()
mm/migrate_device.c: refactor migrate_vma and migrate_deivce_coherent_page()
mm/memremap.c: take a pgmap reference on page allocation
mm: free device private pages have zero refcount
mm/memory.c: fix race when faulting a device private page
mm/damon: use damon_sz_region() in appropriate place
mm/damon: move sz_damon_region to damon_sz_region
lib/test_meminit: add checks for the allocation functions
...
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After hugetlb_pte_stable() introduced, we can also rewrite the migration
race condition against page allocation to use the new helper too.
Link: https://lkml.kernel.org/r/20221004193400.110155-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/hugetlb: Fix selftest failures with write check", v3.
Currently akpm mm-unstable fails with uffd hugetlb private mapping test
randomly on a write check.
The initial bisection of that points to the recent pmd unshare series, but
it turns out there's no direction relationship with the series but only
some timing change caused the race to start trigger.
The race should be fixed in patch 1. Patch 2 is a trivial cleanup on the
similar race with hugetlb migrations, patch 3 comment on the write check
so when anyone read it again it'll be clear why it's there.
This patch (of 3):
After the recent rework patchset of hugetlb locking on pmd sharing,
kselftest for userfaultfd sometimes fails on hugetlb private tests with
unexpected write fault checks.
It turns out there's nothing wrong within the locking series regarding
this matter, but it could have changed the timing of threads so it can
trigger an old bug.
The real bug is when we call hugetlb_no_page() we're not with the pgtable
lock. It means we're reading the pte values lockless. It's perfectly
fine in most cases because before we do normal page allocations we'll take
the lock and check pte_same() again. However before that, there are
actually two paths on userfaultfd missing/minor handling that may directly
move on with the fault process without checking the pte values.
It means for these two paths we may be generating an uffd message based on
an unstable pte, while an unstable pte can legally be anything as long as
the modifier holds the pgtable lock.
One example, which is also what happened in the failing kselftest and
caused the test failure, is that for private mappings wr-protection
changes can happen on one page. While hugetlb_change_protection()
generally requires pte being cleared before being changed, then there can
be a race condition like:
thread 1 thread 2
-------- --------
UFFDIO_WRITEPROTECT hugetlb_fault
hugetlb_change_protection
pgtable_lock()
huge_ptep_modify_prot_start
pte==NULL
hugetlb_no_page
generate uffd missing event
even if page existed!!
huge_ptep_modify_prot_commit
pgtable_unlock()
Fix this by rechecking the pte after pgtable lock for both userfaultfd
missing & minor fault paths.
This bug should have been around starting from uffd hugetlb introduced, so
attaching a Fixes to the commit. Also attach another Fixes to the minor
support commit for easier tracking.
Note that userfaultfd is actually fine with false positives (e.g. caused
by pte changed), but not wrong logical events (e.g. caused by reading a
pte during changing). The latter can confuse the userspace, so the
strictness is very much preferred. E.g., MISSING event should never
happen on the page after UFFDIO_COPY has correctly installed the page and
returned.
Link: https://lkml.kernel.org/r/20221004193400.110155-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20221004193400.110155-2-peterx@redhat.com
Fixes: 1a1aad8a9b7b ("userfaultfd: hugetlbfs: add userfaultfd hugetlb hook")
Fixes: 7677f7fd8be7 ("userfaultfd: add minor fault registration mode")
Signed-off-by: Peter Xu <peterx@redhat.com>
Co-developed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When PTE_MARKER_UFFD_WP not configured, it's still possible to reach pte
marker code and trigger an warning. Add a few CONFIG_PTE_MARKER_UFFD_WP
ifdefs to make sure the code won't be reached when not compiled in.
Link: https://lkml.kernel.org/r/YzeR+R6b4bwBlBHh@x1n
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: |
