The quilt patch titled
Subject: mm: memory-failure: fix unexpected return value in soft_offline_page()
has been removed from the -mm tree. Its filename was
mm-memory-failure-fix-unexpected-return-value-in-soft_offline_page.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: Miaohe Lin <linmiaohe(a)huawei.com>
Subject: mm: memory-failure: fix unexpected return value in soft_offline_page()
Date: Tue, 27 Jun 2023 19:28:08 +0800
When page_handle_poison() fails to handle the hugepage or free page in
retry path, soft_offline_page() will return 0 while -EBUSY is expected in
this case.
Consequently the user will think soft_offline_page succeeds while it in
fact failed. So the user will not try again later in this case.
Link: https://lkml.kernel.org/r/20230627112808.1275241-1-linmiaohe@huawei.com
Fixes: b94e02822deb ("mm,hwpoison: try to narrow window race for free pages")
Signed-off-by: Miaohe Lin <linmiaohe(a)huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi(a)nec.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/memory-failure.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/mm/memory-failure.c~mm-memory-failure-fix-unexpected-return-value-in-soft_offline_page
+++ a/mm/memory-failure.c
@@ -2741,10 +2741,13 @@ retry:
if (ret > 0) {
ret = soft_offline_in_use_page(page);
} else if (ret == 0) {
- if (!page_handle_poison(page, true, false) && try_again) {
- try_again = false;
- flags &= ~MF_COUNT_INCREASED;
- goto retry;
+ if (!page_handle_poison(page, true, false)) {
+ if (try_again) {
+ try_again = false;
+ flags &= ~MF_COUNT_INCREASED;
+ goto retry;
+ }
+ ret = -EBUSY;
}
}
_
Patches currently in -mm which might be from linmiaohe(a)huawei.com are
mm-memory-failure-fix-potential-page-refcnt-leak-in-memory_failure.patch
mm-memcg-fix-obsolete-function-name-in-mem_cgroup_protection.patch
mm-memory-failure-add-pageoffline-check.patch
mm-page_alloc-avoid-unneeded-alike_pages-calculation.patch
mm-memcg-update-obsolete-comment-above-parent_mem_cgroup.patch
mm-page_alloc-remove-unneeded-variable-base.patch
mm-memcg-fix-wrong-function-name-above-obj_cgroup_charge_zswap.patch
mm-memory-failure-use-helper-macro-llist_for_each_entry_safe.patch
mm-mm_init-use-helper-macro-bits_per_long-and-bits_per_byte.patch
The quilt patch titled
Subject: radix tree: remove unused variable
has been removed from the -mm tree. Its filename was
radix-tree-remove-unused-variable.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: Arnd Bergmann <arnd(a)arndb.de>
Subject: radix tree: remove unused variable
Date: Fri, 11 Aug 2023 15:10:13 +0200
Recent versions of clang warn about an unused variable, though older
versions saw the 'slot++' as a use and did not warn:
radix-tree.c:1136:50: error: parameter 'slot' set but not used [-Werror,-Wunused-but-set-parameter]
It's clearly not needed any more, so just remove it.
Link: https://lkml.kernel.org/r/20230811131023.2226509-1-arnd@kernel.org
Fixes: 3a08cd52c37c7 ("radix tree: Remove multiorder support")
Signed-off-by: Arnd Bergmann <arnd(a)arndb.de>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Nathan Chancellor <nathan(a)kernel.org>
Cc: Nick Desaulniers <ndesaulniers(a)google.com>
Cc: Peng Zhang <zhangpeng.00(a)bytedance.com>
Cc: Rong Tao <rongtao(a)cestc.cn>
Cc: Tom Rix <trix(a)redhat.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
lib/radix-tree.c | 1 -
1 file changed, 1 deletion(-)
--- a/lib/radix-tree.c~radix-tree-remove-unused-variable
+++ a/lib/radix-tree.c
@@ -1136,7 +1136,6 @@ static void set_iter_tags(struct radix_t
void __rcu **radix_tree_iter_resume(void __rcu **slot,
struct radix_tree_iter *iter)
{
- slot++;
iter->index = __radix_tree_iter_add(iter, 1);
iter->next_index = iter->index;
iter->tags = 0;
_
Patches currently in -mm which might be from arnd(a)arndb.de are
iomem-remove-__weak-ioremap_cache-helper.patch
The quilt patch titled
Subject: mm: add a call to flush_cache_vmap() in vmap_pfn()
has been removed from the -mm tree. Its filename was
mm-add-a-call-to-flush_cache_vmap-in-vmap_pfn.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: Alexandre Ghiti <alexghiti(a)rivosinc.com>
Subject: mm: add a call to flush_cache_vmap() in vmap_pfn()
Date: Wed, 9 Aug 2023 18:46:33 +0200
flush_cache_vmap() must be called after new vmalloc mappings are installed
in the page table in order to allow architectures to make sure the new
mapping is visible.
It could lead to a panic since on some architectures (like powerpc),
the page table walker could see the wrong pte value and trigger a
spurious page fault that can not be resolved (see commit f1cb8f9beba8
("powerpc/64s/radix: avoid ptesync after set_pte and
ptep_set_access_flags")).
But actually the patch is aiming at riscv: the riscv specification
allows the caching of invalid entries in the TLB, and since we recently
removed the vmalloc page fault handling, we now need to emit a tlb
shootdown whenever a new vmalloc mapping is emitted
(https://lore.kernel.org/linux-riscv/20230725132246.817726-1-alexghiti@rivos…).
That's a temporary solution, there are ways to avoid that :)
Link: https://lkml.kernel.org/r/20230809164633.1556126-1-alexghiti@rivosinc.com
Fixes: 3e9a9e256b1e ("mm: add a vmap_pfn function")
Reported-by: Dylan Jhong <dylan(a)andestech.com>
Closes: https://lore.kernel.org/linux-riscv/ZMytNY2J8iyjbPPy@atctrx.andestech.com/
Signed-off-by: Alexandre Ghiti <alexghiti(a)rivosinc.com>
Reviewed-by: Christoph Hellwig <hch(a)lst.de>
Reviewed-by: Palmer Dabbelt <palmer(a)rivosinc.com>
Acked-by: Palmer Dabbelt <palmer(a)rivosinc.com>
Reviewed-by: Dylan Jhong <dylan(a)andestech.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/vmalloc.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/vmalloc.c~mm-add-a-call-to-flush_cache_vmap-in-vmap_pfn
+++ a/mm/vmalloc.c
@@ -2979,6 +2979,10 @@ void *vmap_pfn(unsigned long *pfns, unsi
free_vm_area(area);
return NULL;
}
+
+ flush_cache_vmap((unsigned long)area->addr,
+ (unsigned long)area->addr + count * PAGE_SIZE);
+
return area->addr;
}
EXPORT_SYMBOL_GPL(vmap_pfn);
_
Patches currently in -mm which might be from alexghiti(a)rivosinc.com are
The quilt patch titled
Subject: selftests/mm: FOLL_LONGTERM need to be updated to 0x100
has been removed from the -mm tree. Its filename was
selftests-mm-foll_longterm-need-to-be-updated-to-0x100.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: Ayush Jain <ayush.jain3(a)amd.com>
Subject: selftests/mm: FOLL_LONGTERM need to be updated to 0x100
Date: Tue, 8 Aug 2023 07:43:47 -0500
After commit 2c2241081f7d ("mm/gup: move private gup FOLL_ flags to
internal.h") FOLL_LONGTERM flag value got updated from 0x10000 to 0x100 at
include/linux/mm_types.h.
As hmm.hmm_device_private.hmm_gup_test uses FOLL_LONGTERM Updating same
here as well.
Before this change test goes in an infinite assert loop in
hmm.hmm_device_private.hmm_gup_test
==========================================================
RUN hmm.hmm_device_private.hmm_gup_test ...
hmm-tests.c:1962:hmm_gup_test:Expected HMM_DMIRROR_PROT_WRITE..
..(2) == m[2] (34)
hmm-tests.c:157:hmm_gup_test:Expected ret (-1) == 0 (0)
hmm-tests.c:157:hmm_gup_test:Expected ret (-1) == 0 (0)
...
==========================================================
Call Trace:
<TASK>
? sched_clock+0xd/0x20
? __lock_acquire.constprop.0+0x120/0x6c0
? ktime_get+0x2c/0xd0
? sched_clock+0xd/0x20
? local_clock+0x12/0xd0
? lock_release+0x26e/0x3b0
pin_user_pages_fast+0x4c/0x70
gup_test_ioctl+0x4ff/0xbb0
? gup_test_ioctl+0x68c/0xbb0
__x64_sys_ioctl+0x99/0xd0
do_syscall_64+0x60/0x90
? syscall_exit_to_user_mode+0x2a/0x50
? do_syscall_64+0x6d/0x90
? syscall_exit_to_user_mode+0x2a/0x50
? do_syscall_64+0x6d/0x90
? irqentry_exit_to_user_mode+0xd/0x20
? irqentry_exit+0x3f/0x50
? exc_page_fault+0x96/0x200
entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f6aaa31aaff
After this change test is able to pass successfully.
Link: https://lkml.kernel.org/r/20230808124347.79163-1-ayush.jain3@amd.com
Fixes: 2c2241081f7d ("mm/gup: move private gup FOLL_ flags to internal.h")
Signed-off-by: Ayush Jain <ayush.jain3(a)amd.com>
Reviewed-by: Raghavendra K T <raghavendra.kt(a)amd.com>
Reviewed-by: John Hubbard <jhubbard(a)nvidia.com>
Acked-by: David Hildenbrand <david(a)redhat.com>
Cc: Jason Gunthorpe <jgg(a)nvidia.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
tools/testing/selftests/mm/hmm-tests.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/mm/hmm-tests.c~selftests-mm-foll_longterm-need-to-be-updated-to-0x100
+++ a/tools/testing/selftests/mm/hmm-tests.c
@@ -57,9 +57,14 @@ enum {
#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
/* Just the flags we need, copied from mm.h: */
+
+#ifndef FOLL_WRITE
#define FOLL_WRITE 0x01 /* check pte is writable */
-#define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite */
+#endif
+#ifndef FOLL_LONGTERM
+#define FOLL_LONGTERM 0x100 /* mapping lifetime is indefinite */
+#endif
FIXTURE(hmm)
{
int fd;
_
Patches currently in -mm which might be from ayush.jain3(a)amd.com are
selftests-mm-add-ksm_merge_time-tests.patch
The quilt patch titled
Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers()
has been removed from the -mm tree. Its filename was
nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers.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: Ryusuke Konishi <konishi.ryusuke(a)gmail.com>
Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers()
Date: Sat, 5 Aug 2023 22:20:38 +0900
A syzbot stress test reported that create_empty_buffers() called from
nilfs_lookup_dirty_data_buffers() can cause a general protection fault.
Analysis using its reproducer revealed that the back reference "mapping"
from a page/folio has been changed to NULL after dirty page/folio gang
lookup in nilfs_lookup_dirty_data_buffers().
Fix this issue by excluding pages/folios from being collected if, after
acquiring a lock on each page/folio, its back reference "mapping" differs
from the pointer to the address space struct that held the page/folio.
Link: https://lkml.kernel.org/r/20230805132038.6435-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke(a)gmail.com>
Reported-by: syzbot+0ad741797f4565e7e2d2(a)syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/0000000000002930a705fc32b231@google.com
Tested-by: Ryusuke Konishi <konishi.ryusuke(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/nilfs2/segment.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/fs/nilfs2/segment.c~nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers
+++ a/fs/nilfs2/segment.c
@@ -725,6 +725,11 @@ static size_t nilfs_lookup_dirty_data_bu
struct folio *folio = fbatch.folios[i];
folio_lock(folio);
+ if (unlikely(folio->mapping != mapping)) {
+ /* Exclude folios removed from the address space */
+ folio_unlock(folio);
+ continue;
+ }
head = folio_buffers(folio);
if (!head) {
create_empty_buffers(&folio->page, i_blocksize(inode), 0);
_
Patches currently in -mm which might be from konishi.ryusuke(a)gmail.com are
nilfs2-fix-warning-in-mark_buffer_dirty-due-to-discarded-buffer-reuse.patch
The quilt patch titled
Subject: mm/gup: handle cont-PTE hugetlb pages correctly in gup_must_unshare() via GUP-fast
has been removed from the -mm tree. Its filename was
mm-gup-handle-cont-pte-hugetlb-pages-correctly-in-gup_must_unshare-via-gup-fast.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: David Hildenbrand <david(a)redhat.com>
Subject: mm/gup: handle cont-PTE hugetlb pages correctly in gup_must_unshare() via GUP-fast
Date: Sat, 5 Aug 2023 12:12:56 +0200
In contrast to most other GUP code, GUP-fast common page table walking
code like gup_pte_range() also handles hugetlb pages. But in contrast to
other hugetlb page table walking code, it does not look at the hugetlb PTE
abstraction whereby we have only a single logical hugetlb PTE per hugetlb
page, even when using multiple cont-PTEs underneath -- which is for
example what huge_ptep_get() abstracts.
So when we have a hugetlb page that is mapped via cont-PTEs, GUP-fast
might stumble over a PTE that does not map the head page of a hugetlb page
-- not the first "head" PTE of such a cont mapping.
Logically, the whole hugetlb page is mapped (entire_mapcount == 1), but we
might end up calling gup_must_unshare() with a tail page of a hugetlb
page.
We only maintain a single PageAnonExclusive flag per hugetlb page (as
hugetlb pages cannot get partially COW-shared), stored for the head page.
That flag is clear for all tail pages.
So when gup_must_unshare() ends up calling PageAnonExclusive() with a tail
page of a hugetlb page:
1) With CONFIG_DEBUG_VM_PGFLAGS
Stumbles over the:
VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
For example, when executing the COW selftests with 64k hugetlb pages on
arm64:
[ 61.082187] page:00000000829819ff refcount:3 mapcount:1 mapping:0000000000000000 index:0x1 pfn:0x11ee11
[ 61.082842] head:0000000080f79bf7 order:4 entire_mapcount:1 nr_pages_mapped:0 pincount:2
[ 61.083384] anon flags: 0x17ffff80003000e(referenced|uptodate|dirty|head|mappedtodisk|node=0|zone=2|lastcpupid=0xfffff)
[ 61.084101] page_type: 0xffffffff()
[ 61.084332] raw: 017ffff800000000 fffffc00037b8401 0000000000000402 0000000200000000
[ 61.084840] raw: 0000000000000010 0000000000000000 00000000ffffffff 0000000000000000
[ 61.085359] head: 017ffff80003000e ffffd9e95b09b788 ffffd9e95b09b788 ffff0007ff63cf71
[ 61.085885] head: 0000000000000000 0000000000000002 00000003ffffffff 0000000000000000
[ 61.086415] page dumped because: VM_BUG_ON_PAGE(PageHuge(page) && !PageHead(page))
[ 61.086914] ------------[ cut here ]------------
[ 61.087220] kernel BUG at include/linux/page-flags.h:990!
[ 61.087591] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
[ 61.087999] Modules linked in: ...
[ 61.089404] CPU: 0 PID: 4612 Comm: cow Kdump: loaded Not tainted 6.5.0-rc4+ #3
[ 61.089917] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[ 61.090409] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 61.090897] pc : gup_must_unshare.part.0+0x64/0x98
[ 61.091242] lr : gup_must_unshare.part.0+0x64/0x98
[ 61.091592] sp : ffff8000825eb940
[ 61.091826] x29: ffff8000825eb940 x28: 0000000000000000 x27: fffffc00037b8440
[ 61.092329] x26: 0400000000000001 x25: 0000000000080101 x24: 0000000000080000
[ 61.092835] x23: 0000000000080100 x22: ffff0000cffb9588 x21: ffff0000c8ec6b58
[ 61.093341] x20: 0000ffffad6b1000 x19: fffffc00037b8440 x18: ffffffffffffffff
[ 61.093850] x17: 2864616548656761 x16: 5021202626202965 x15: 6761702865677548
[ 61.094358] x14: 6567615028454741 x13: 2929656761702864 x12: 6165486567615021
[ 61.094858] x11: 00000000ffff7fff x10: 00000000ffff7fff x9 : ffffd9e958b7a1c0
[ 61.095359] x8 : 00000000000bffe8 x7 : c0000000ffff7fff x6 : 00000000002bffa8
[ 61.095873] x5 : ffff0008bb19e708 x4 : 0000000000000000 x3 : 0000000000000000
[ 61.096380] x2 : 0000000000000000 x1 : ffff0000cf6636c0 x0 : 0000000000000046
[ 61.096894] Call trace:
[ 61.097080] gup_must_unshare.part.0+0x64/0x98
[ 61.097392] gup_pte_range+0x3a8/0x3f0
[ 61.097662] gup_pgd_range+0x1ec/0x280
[ 61.097942] lockless_pages_from_mm+0x64/0x1a0
[ 61.098258] internal_get_user_pages_fast+0xe4/0x1d0
[ 61.098612] pin_user_pages_fast+0x58/0x78
[ 61.098917] pin_longterm_test_start+0xf4/0x2b8
[ 61.099243] gup_test_ioctl+0x170/0x3b0
[ 61.099528] __arm64_sys_ioctl+0xa8/0xf0
[ 61.099822] invoke_syscall.constprop.0+0x7c/0xd0
[ 61.100160] el0_svc_common.constprop.0+0xe8/0x100
[ 61.100500] do_el0_svc+0x38/0xa0
[ 61.100736] el0_svc+0x3c/0x198
[ 61.100971] el0t_64_sync_handler+0x134/0x150
[ 61.101280] el0t_64_sync+0x17c/0x180
[ 61.101543] Code: aa1303e0 f00074c1 912b0021 97fffeb2 (d4210000)
2) Without CONFIG_DEBUG_VM_PGFLAGS
Always detects "not exclusive" for passed tail pages and refuses to PIN
the tail pages R/O, as gup_must_unshare() == true. GUP-fast will fallback
to ordinary GUP. As ordinary GUP properly considers the logical hugetlb
PTE abstraction in hugetlb_follow_page_mask(), pinning the page will
succeed when looking at the PageAnonExclusive on the head page only.
So the only real effect of this is that with cont-PTE hugetlb pages, we'll
always fallback from GUP-fast to ordinary GUP when not working on the head
page, which ends up checking the head page and do the right thing.
Consequently, the cow selftests pass with cont-PTE hugetlb pages as well
without CONFIG_DEBUG_VM_PGFLAGS.
Note that this only applies to anon hugetlb pages that are mapped using
cont-PTEs: for example 64k hugetlb pages on a 4k arm64 kernel.
... and only when R/O-pinning (FOLL_PIN) such pages that are mapped into
the page table R/O using GUP-fast.
On production kernels (and even most debug kernels, that don't set
CONFIG_DEBUG_VM_PGFLAGS) this patch should theoretically not be required
to be backported. But of course, it does not hurt.
Link: https://lkml.kernel.org/r/20230805101256.87306-1-david@redhat.com
Fixes: a7f226604170 ("mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Reported-by: Ryan Roberts <ryan.roberts(a)arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts(a)arm.com>
Tested-by: Ryan Roberts <ryan.roberts(a)arm.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: John Hubbard <jhubbard(a)nvidia.com>
Cc: Jason Gunthorpe <jgg(a)nvidia.com>
Cc: Peter Xu <peterx(a)redhat.com>
Cc: Mike Kravetz <mike.kravetz(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/internal.h | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/mm/internal.h~mm-gup-handle-cont-pte-hugetlb-pages-correctly-in-gup_must_unshare-via-gup-fast
+++ a/mm/internal.h
@@ -1005,6 +1005,16 @@ static inline bool gup_must_unshare(stru
smp_rmb();
/*
+ * During GUP-fast we might not get called on the head page for a
+ * hugetlb page that is mapped using cont-PTE, because GUP-fast does
+ * not work with the abstracted hugetlb PTEs that always point at the
+ * head page. For hugetlb, PageAnonExclusive only applies on the head
+ * page (as it cannot be partially COW-shared), so lookup the head page.
+ */
+ if (unlikely(!PageHead(page) && PageHuge(page)))
+ page = compound_head(page);
+
+ /*
* Note that PageKsm() pages cannot be exclusive, and consequently,
* cannot get pinned.
*/
_
Patches currently in -mm which might be from david(a)redhat.com are
kvm-explicitly-set-foll_honor_numa_fault-in-hva_to_pfn_slow.patch
mm-gup-dont-implicitly-set-foll_honor_numa_fault.patch
pgtable-improve-pte_protnone-comment.patch
selftest-mm-ksm_functional_tests-test-in-mmap_and_merge_range-if-anything-got-merged.patch
selftest-mm-ksm_functional_tests-add-prot_none-test.patch
selftest-mm-ksm_functional_tests-add-prot_none-test-fix.patch
mm-swap-stop-using-page-private-on-tail-pages-for-thp_swap.patch
mm-swap-inline-folio_set_swap_entry-and-folio_swap_entry.patch
mm-huge_memory-work-on-folio-swap-instead-of-page-private-when-splitting-folio.patch
The quilt patch titled
Subject: mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT
has been removed from the -mm tree. Its filename was
mm-gup-reintroduce-foll_numa-as-foll_honor_numa_fault.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: David Hildenbrand <david(a)redhat.com>
Subject: mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT
Date: Thu, 3 Aug 2023 16:32:02 +0200
Unfortunately commit 474098edac26 ("mm/gup: replace FOLL_NUMA by
gup_can_follow_protnone()") missed that follow_page() and
follow_trans_huge_pmd() never implicitly set FOLL_NUMA because they really
don't want to fail on PROT_NONE-mapped pages -- either due to NUMA hinting
or due to inaccessible (PROT_NONE) VMAs.
As spelled out in commit 0b9d705297b2 ("mm: numa: Support NUMA hinting
page faults from gup/gup_fast"): "Other follow_page callers like KSM
should not use FOLL_NUMA, or they would fail to get the pages if they use
follow_page instead of get_user_pages."
liubo reported [1] that smaps_rollup results are imprecise, because they
miss accounting of pages that are mapped PROT_NONE. Further, it's easy to
reproduce that KSM no longer works on inaccessible VMAs on x86-64, because
pte_protnone()/pmd_protnone() also indictaes "true" in inaccessible VMAs,
and follow_page() refuses to return such pages right now.
As KVM really depends on these NUMA hinting faults, removing the
pte_protnone()/pmd_protnone() handling in GUP code completely is not
really an option.
To fix the issues at hand, let's revive FOLL_NUMA as FOLL_HONOR_NUMA_FAULT
to restore the original behavior for now and add better comments.
Set FOLL_HONOR_NUMA_FAULT independent of FOLL_FORCE in
is_valid_gup_args(), to add that flag for all external GUP users.
Note that there are three GUP-internal __get_user_pages() users that don't
end up calling is_valid_gup_args() and consequently won't get
FOLL_HONOR_NUMA_FAULT set.
1) get_dump_page(): we really don't want to handle NUMA hinting
faults. It specifies FOLL_FORCE and wouldn't have honored NUMA
hinting faults already.
2) populate_vma_page_range(): we really don't want to handle NUMA hinting
faults. It specifies FOLL_FORCE on accessible VMAs, so it wouldn't have
honored NUMA hinting faults already.
3) faultin_vma_page_range(): we similarly don't want to handle NUMA
hinting faults.
To make the combination of FOLL_FORCE and FOLL_HONOR_NUMA_FAULT work in
inaccessible VMAs properly, we have to perform VMA accessibility checks in
gup_can_follow_protnone().
As GUP-fast should reject such pages either way in
pte_access_permitted()/pmd_access_permitted() -- for example on x86-64 and
arm64 that both implement pte_protnone() -- let's just always fallback to
ordinary GUP when stumbling over pte_protnone()/pmd_protnone().
As Linus notes [2], honoring NUMA faults might only make sense for
selected GUP users.
So we should really see if we can instead let relevant GUP callers specify
it manually, and not trigger NUMA hinting faults from GUP as default.
Prepare for that by making FOLL_HONOR_NUMA_FAULT an external GUP flag and
adding appropriate documenation.
While at it, remove a stale comment from follow_trans_huge_pmd(): That
comment for pmd_protnone() was added in commit 2b4847e73004 ("mm: numa:
serialise parallel get_user_page against THP migration"), which noted:
THP does not unmap pages due to a lack of support for migration
entries at a PMD level. This allows races with get_user_pages
Nowadays, we do have PMD migration entries, so the comment no longer
applies. Let's drop it.
[1] https://lore.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com
[2] https://lore.kernel.org/r/CAHk-=wgRiP_9X0rRdZKT8nhemZGNateMtb366t37d8-x7VRs…
Link: https://lkml.kernel.org/r/20230803143208.383663-2-david@redhat.com
Fixes: 474098edac26 ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Reported-by: liubo <liubo254(a)huawei.com>
Closes: https://lore.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com
Reported-by: Peter Xu <peterx(a)redhat.com>
Closes: https://lore.kernel.org/all/ZMKJjDaqZ7FW0jfe@x1n/
Acked-by: Mel Gorman <mgorman(a)techsingularity.net>
Acked-by: Peter Xu <peterx(a)redhat.com>
Cc: Hugh Dickins <hughd(a)google.com>
Cc: Jason Gunthorpe <jgg(a)ziepe.ca>
Cc: John Hubbard <jhubbard(a)nvidia.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org>
Cc: Mel Gorman <mgorman(a)suse.de>
Cc: Paolo Bonzini <pbonzini(a)redhat.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
include/linux/mm.h | 21 +++++++++++++++------
include/linux/mm_types.h | 9 +++++++++
mm/gup.c | 30 ++++++++++++++++++++++++------
mm/huge_memory.c | 3 +--
4 files changed, 49 insertions(+), 14 deletions(-)
--- a/include/linux/mm.h~mm-gup-reintroduce-foll_numa-as-foll_honor_numa_fault
+++ a/include/linux/mm.h
@@ -3421,15 +3421,24 @@ static inline int vm_fault_to_errno(vm_f
* Indicates whether GUP can follow a PROT_NONE mapped page, or whether
* a (NUMA hinting) fault is required.
*/
-static inline bool gup_can_follow_protnone(unsigned int flags)
+static inline bool gup_can_follow_protnone(struct vm_area_struct *vma,
+ unsigned int flags)
{
/*
- * FOLL_FORCE has to be able to make progress even if the VMA is
- * inaccessible. Further, FOLL_FORCE access usually does not represent
- * application behaviour and we should avoid triggering NUMA hinting
- * faults.
+ * If callers don't want to honor NUMA hinting faults, no need to
+ * determine if we would actually have to trigger a NUMA hinting fault.
*/
- return flags & FOLL_FORCE;
+ if (!(flags & FOLL_HONOR_NUMA_FAULT))
+ return true;
+
+ /*
+ * NUMA hinting faults don't apply in inaccessible (PROT_NONE) VMAs.
+ *
+ * Requiring a fault here even for inaccessible VMAs would mean that
+ * FOLL_FORCE cannot make any progress, because handle_mm_fault()
+ * refuses to process NUMA hinting faults in inaccessible VMAs.
+ */
+ return !vma_is_accessible(vma);
}
typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data);
--- a/include/linux/mm_types.h~mm-gup-reintroduce-foll_numa-as-foll_honor_numa_fault
+++ a/include/linux/mm_types.h
@@ -1286,6 +1286,15 @@ enum {
FOLL_PCI_P2PDMA = 1 << 10,
/* allow interrupts from generic signals */
FOLL_INTERRUPTIBLE = 1 << 11,
+ /*
+ * Always honor (trigger) NUMA hinting faults.
+ *
+ * FOLL_WRITE implicitly honors NUMA hinting faults because a
+ * PROT_NONE-mapped page is not writable (exceptions with FOLL_FORCE
+ * apply). get_user_pages_fast_only() always implicitly honors NUMA
+ * hinting faults.
+ */
+ FOLL_HONOR_NUMA_FAULT = 1 << 12,
/* See also internal only FOLL flags in mm/internal.h */
};
--- a/mm/gup.c~mm-gup-reintroduce-foll_numa-as-foll_honor_numa_fault
+++ a/mm/gup.c
@@ -597,7 +597,7 @@ static struct page *follow_page_pte(stru
pte = ptep_get(ptep);
if (!pte_present(pte))
goto no_page;
- if (pte_protnone(pte) && !gup_can_follow_protnone(flags))
+ if (pte_protnone(pte) && !gup_can_follow_protnone(vma, flags))
goto no_page;
page = vm_normal_page(vma, address, pte);
@@ -714,7 +714,7 @@ static struct page *follow_pmd_mask(stru
if (likely(!pmd_trans_huge(pmdval)))
return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
- if (pmd_protnone(pmdval) && !gup_can_follow_protnone(flags))
+ if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))
return no_page_table(vma, flags);
ptl = pmd_lock(mm, pmd);
@@ -851,6 +851,10 @@ struct page *follow_page(struct vm_area_
if (WARN_ON_ONCE(foll_flags & FOLL_PIN))
return NULL;
+ /*
+ * We never set FOLL_HONOR_NUMA_FAULT because callers don't expect
+ * to fail on PROT_NONE-mapped pages.
+ */
page = follow_page_mask(vma, address, foll_flags, &ctx);
if (ctx.pgmap)
put_dev_pagemap(ctx.pgmap);
@@ -2227,6 +2231,13 @@ static bool is_valid_gup_args(struct pag
gup_flags |= FOLL_UNLOCKABLE;
}
+ /*
+ * For now, always trigger NUMA hinting faults. Some GUP users like
+ * KVM require the hint to be as the calling context of GUP is
+ * functionally similar to a memory reference from task context.
+ */
+ gup_flags |= FOLL_HONOR_NUMA_FAULT;
+
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
if (WARN_ON_ONCE((gup_flags & (FOLL_PIN | FOLL_GET)) ==
(FOLL_PIN | FOLL_GET)))
@@ -2551,7 +2562,14 @@ static int gup_pte_range(pmd_t pmd, pmd_
struct page *page;
struct folio *folio;
- if (pte_protnone(pte) && !gup_can_follow_protnone(flags))
+ /*
+ * Always fallback to ordinary GUP on PROT_NONE-mapped pages:
+ * pte_access_permitted() better should reject these pages
+ * either way: otherwise, GUP-fast might succeed in
+ * cases where ordinary GUP would fail due to VMA access
+ * permissions.
+ */
+ if (pte_protnone(pte))
goto pte_unmap;
if (!pte_access_permitted(pte, flags & FOLL_WRITE))
@@ -2970,8 +2988,8 @@ static int gup_pmd_range(pud_t *pudp, pu
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
pmd_devmap(pmd))) {
- if (pmd_protnone(pmd) &&
- !gup_can_follow_protnone(flags))
+ /* See gup_pte_range() */
+ if (pmd_protnone(pmd))
return 0;
if (!gup_huge_pmd(pmd, pmdp, addr, next, flags,
@@ -3151,7 +3169,7 @@ static int internal_get_user_pages_fast(
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET |
FOLL_FAST_ONLY | FOLL_NOFAULT |
- FOLL_PCI_P2PDMA)))
+ FOLL_PCI_P2PDMA | FOLL_HONOR_NUMA_FAULT)))
return -EINVAL;
if (gup_flags & FOLL_PIN)
--- a/mm/huge_memory.c~mm-gup-reintroduce-foll_numa-as-foll_honor_numa_fault
+++ a/mm/huge_memory.c
@@ -1467,8 +1467,7 @@ struct page *follow_trans_huge_pmd(struc
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
return ERR_PTR(-EFAULT);
- /* Full NUMA hinting faults to serialise migration in fault paths */
- if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags))
+ if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags))
return NULL;
if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page))
_
Patches currently in -mm which might be from david(a)redhat.com are
kvm-explicitly-set-foll_honor_numa_fault-in-hva_to_pfn_slow.patch
mm-gup-dont-implicitly-set-foll_honor_numa_fault.patch
pgtable-improve-pte_protnone-comment.patch
selftest-mm-ksm_functional_tests-test-in-mmap_and_merge_range-if-anything-got-merged.patch
selftest-mm-ksm_functional_tests-add-prot_none-test.patch
selftest-mm-ksm_functional_tests-add-prot_none-test-fix.patch
mm-swap-stop-using-page-private-on-tail-pages-for-thp_swap.patch
mm-swap-inline-folio_set_swap_entry-and-folio_swap_entry.patch
mm-huge_memory-work-on-folio-swap-instead-of-page-private-when-splitting-folio.patch