try_alloc_pages() will not attempt to allocate memory if the system has
*any* unaccepted memory. Memory is accepted as needed and can remain in
the system indefinitely, causing the interface to always fail.

Rather than immediately giving up, attempt to use already accepted memory
on free lists.

Pass 'alloc_flags' to cond_accept_memory() and do not accept new memory
for ALLOC_TRYLOCK requests.

Found via code inspection - only BPF uses this at present and the
runtime effects are unclear.

Link: https://lkml.kernel.org/r/20250506112509.905147-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

As part of the ongoing efforts to sub-divide memory management
maintainership and reviewership, establish a section for GUP (Get User
Pages) support and add appropriate maintainers and reviewers.

Link: https://lkml.kernel.org/r/20250506173601.97562-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Commit 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled()
checks") introduces a possible use-after-free scenario, when page
is non-compound, page[0] could be released by other thread right
after put_page_testzero failed in current thread, pgalloc_tag_sub_pages
afterwards would manipulate an invalid page for accounting remaining
pages:

[timeline] [thread1] [thread2]
| alloc_page non-compound
V
| get_page, rf counter inc
V
| in ___free_pages
| put_page_testzero fails
V
| put_page, page released
V
| in ___free_pages,
| pgalloc_tag_sub_pages
| manipulate an invalid page
V

Restore __free_pages() to its state before, retrieve alloc tag
beforehand.

Link: https://lkml.kernel.org/r/20250505193034.91682-1-00107082@163.com
Fixes: 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled() checks")
Signed-off-by: David Wang <00107082@163.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The following WARNING was triggered during swap stress test with mTHP
enabled:

[ 6609.335758] ------------[ cut here ]------------
[ 6609.337758] WARNING: CPU: 82 PID: 755116 at mm/memory.c:3794 do_wp_page+0x1084/0x10e0
[ 6609.340922] Modules linked in: zram virtiofs
[ 6609.342699] CPU: 82 UID: 0 PID: 755116 Comm: sh Kdump: loaded Not tainted 6.15.0-rc1+ #1429 PREEMPT(voluntary)
[ 6609.347620] Hardware name: Red Hat KVM/RHEL-AV, BIOS 0.0.0 02/06/2015
[ 6609.349909] RIP: 0010:do_wp_page+0x1084/0x10e0
[ 6609.351532] Code: ff ff 48 c7 c6 80 ba 49 82 4c 89 ef e8 95 fd fe ff 0f 0b bd f5 ff ff ff e9 43 fb ff ff 41 83 a9 bc 12 00 00 01 e9 5c fb ff ff <0f> 0b e9 a6 fc ff ff 65 ff 00 f0 48 0f b
a 6d 00 1f 0f 83 82 fc ff
[ 6609.357959] RSP: 0000:ffffc90002273d40 EFLAGS: 00010287
[ 6609.359915] RAX: 000000000000000f RBX: 0000000000000000 RCX: 000fffffffe00000
[ 6609.362606] RDX: 0000000000000010 RSI: 000055a119ac1000 RDI: ffffea000ae6ec00
[ 6609.365143] RBP: ffffea000ae6ec68 R08: 84000002b9bb1025 R09: 000055a119ab6000
[ 6609.367569] R10: ffff8881caa2ad80 R11: 0000000000000000 R12: ffff8881caa2ad80
[ 6609.370255] R13: ffffea000ae6ec00 R14: 000055a119ac1c9c R15: ffffc90002273dd8
[ 6609.373007] FS: 00007f08e467f740(0000) GS:ffff88a07c214000(0000) knlGS:0000000000000000
[ 6609.375999] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6609.377946] CR2: 000055a119ac1c9c CR3: 00000001adfd6005 CR4: 0000000000770eb0
[ 6609.380376] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 6609.382853] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 6609.385216] PKRU: 55555554
[ 6609.386141] Call Trace:
[ 6609.387017] <TASK>
[ 6609.387718] ? ___pte_offset_map+0x1b/0x110
[ 6609.389056] __handle_mm_fault+0xa51/0xf00
[ 6609.390363] ? exc_page_fault+0x6a/0x140
[ 6609.391629] handle_mm_fault+0x13d/0x360
[ 6609.392856] do_user_addr_fault+0x2f2/0x7f0
[ 6609.394160] ? sigprocmask+0x77/0xa0
[ 6609.395375] exc_page_fault+0x6a/0x140
[ 6609.396735] asm_exc_page_fault+0x26/0x30
[ 6609.398224] RIP: 0033:0x55a1050bc18b
[ 6609.399567] Code: 8b 3f 4d 85 ff 74 40 41 39 5f 18 75 f2 49 8b 7f 08 44 38 27 75 e9 4c 89 c6 4c 89 45 c8 e8 bd 83 fa ff 4c 8b 45 c8 85 c0 75 d5 <41> 83 47 1c 01 48 83 c4 28 4c 89 f8 5b 4
1 5c 41 5d 41 5e 41 5f 5d
[ 6609.405971] RSP: 002b:00007ffcf5f37d90 EFLAGS: 00010246
[ 6609.407737] RAX: 0000000000000000 RBX: 00000000182768fa RCX: 0000000000000000
[ 6609.410151] RDX: 00000000000000fa RSI: 000055a105175c7b RDI: 000055a119ac1c60
[ 6609.412606] RBP: 00007ffcf5f37de0 R08: 000055a105175c7b R09: 0000000000000000
[ 6609.414998] R10: 000000004d2dfb5a R11: 0000000000000246 R12: 0000000000000050
[ 6609.417193] R13: 00000000000000fa R14: 000055a119abaf60 R15: 000055a119ac1c80
[ 6609.419268] </TASK>
[ 6609.419928] ---[ end trace 0000000000000000 ]---

The WARN_ON here is simply incorrect. The refcount here must be at least
the mapcount, not the opposite. Each mapcount must have a corresponding
refcount, but the refcount may increase if other components grab the
folio, which is acceptable. Meanwhile, having a mapcount larger than
refcount is a real problem.

So fix the WARN_ON condition.

Link: https://lkml.kernel.org/r/20250425074325.61833-1-ryncsn@gmail.com
Fixes: 1da190f4d0a6 ("mm: Copy-on-Write (COW) reuse support for PTE-mapped THP")
Signed-off-by: Kairui Song <kasong@tencent.com>
Reported-by: Kairui Song <kasong@tencent.com>
Closes: https://lore.kernel.org/all/CAMgjq7D+ea3eg9gRCVvRnto3Sv3_H3WVhupX4e=k8T5QAfBHbw@mail.gmail.com/
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Not intuitive, but vm_area_dup() located in kernel/fork.c is not only used
for duplicating VMAs during fork(), but also for duplicating VMAs when
splitting VMAs or when mremap()'ing them.

VM_PFNMAP mappings can at least get ordinarily mremap()'ed (no change in
size) and apparently also shrunk during mremap(), which implies
duplicating the VMA in __split_vma() first.

In case of ordinary mremap() (no change in size), we first duplicate the
VMA in copy_vma_and_data()->copy_vma() to then call untrack_pfn_clear() on
the old VMA: we effectively move the VM_PAT reservation. So the
untrack_pfn_clear() call on the new VMA duplicating is wrong in that
context.

Splitting of VMAs seems problematic, because we don't duplicate/adjust the
reservation when splitting the VMA. Instead, in memtype_erase() -- called
during zapping/munmap -- we shrink a reservation in case only the end
address matches: Assume we split a VMA into A and B, both would share a
reservation until B is unmapped.

So when unmapping B, the reservation would be updated to cover only A.
When unmapping A, we would properly remove the now-shrunk reservation.
That scenario describes the mremap() shrinking (old_size > new_size),
where we split + unmap B, and the untrack_pfn_clear() on the new VMA when
is wrong.

What if we manage to split a VM_PFNMAP VMA into A and B and unmap A first?
It would be broken because we would never free the reservation. Likely,
there are ways to trigger such a VMA split outside of mremap().

Affecting other VMA duplication was not intended, vm_area_dup() being used
outside of kernel/fork.c was an oversight. So let's fix that for; how to
handle VMA splits better should be investigated separately.


With a simple reproducer that uses mprotect() to split such a VMA I can
trigger

x86/PAT: pat_mremap:26448 freeing invalid memtype [mem 0x00000000-0x00000fff]

Link: https://lkml.kernel.org/r/20250422144942.2871395-1-david@redhat.com
Fixes: dc84bc2aba85 ("x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

During our testing with hugetlb subpool enabled, we observe that
hstate->resv_huge_pages may underflow into negative values. Root cause
analysis reveals a race condition in subpool reservation fallback handling
as follow:

hugetlb_reserve_pages()
/* Attempt subpool reservation */
gbl_reserve = hugepage_subpool_get_pages(spool, chg);

/* Global reservation may fail after subpool allocation */
if (hugetlb_acct_memory(h, gbl_reserve) < 0)
goto out_put_pages;

out_put_pages:
/* This incorrectly restores reservation to subpool */
hugepage_subpool_put_pages(spool, chg);

When hugetlb_acct_memory() fails after subpool allocation, the current
implementation over-commits subpool reservations by returning the full
'chg' value instead of the actual allocated 'gbl_reserve' amount. This
discrepancy propagates to global reservations during subsequent releases,
eventually causing resv_huge_pages underflow.

This problem can be trigger easily with the following steps:
1. reverse hugepage for hugeltb allocation
2. mount hugetlbfs with min_size to enable hugetlb subpool
3. alloc hugepages with two task(make sure the second will fail due to
insufficient amount of hugepages)
4. with for a few seconds and repeat step 3 which will make
hstate->resv_huge_pages to go below zero.

To fix this problem, return corrent amount of pages to subpool during the
fallback after hugepage_subpool_get_pages is called.

Link: https://lkml.kernel.org/r/20250410062633.3102457-1-mawupeng1@huawei.com
Fixes: 1c5ecae3a93f ("hugetlbfs: add minimum size accounting to subpools")
Signed-off-by: Wupeng Ma <mawupeng1@huawei.com>
Tested-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ma Wupeng <mawupeng1@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Pull KVM fixes from Paolo Bonzini:
"ARM:

- Avoid use of uninitialized memcache pointer in user_mem_abort()

- Always set HCR_EL2.xMO bits when running in VHE, allowing
interrupts to be taken while TGE=0 and fixing an ugly bug on
AmpereOne that occurs when taking an interrupt while clearing the
xMO bits (AC03_CPU_36)

- Prevent VMMs from hiding support for AArch64 at any EL virtualized
by KVM

- Save/restore the host value for HCRX_EL2 instead of restoring an
incorrect fixed value

- Make host_stage2_set_owner_locked() check that the entire requested
range is memory rather than just the first page

RISC-V:

- Add missing reset of smstateen CSRs

x86:

- Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid
causing problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to
sanitize the VMCB as its state is undefined after SHUTDOWN,
emulating INIT is the least awful choice).

- Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
KVM doesn't goof a sanity check in the future.

- Free obsolete roots when (re)loading the MMU to fix a bug where
pre-faulting memory can get stuck due to always encountering a
stale root.

- When dumping GHCB state, use KVM's snapshot instead of the raw GHCB
page to print state, so that KVM doesn't print stale/wrong
information.

- When changing memory attributes (e.g. shared <=> private), add
potential hugepage ranges to the mmu_invalidate_range_{start,end}
set so that KVM doesn't create a shared/private hugepage when the
the corresponding attributes will become mixed (the attributes are
commited *after* KVM finishes the invalidation).

- Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM
has at least one active VM. Effectively BP_SPEC_REDUCE when KVM is
loaded led to very measurable performance regressions for non-KVM
workloads"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: SVM: Set/clear SRSO's BP_SPEC_REDUCE on 0 <=> 1 VM count transitions
KVM: arm64: Fix memory check in host_stage2_set_owner_locked()
KVM: arm64: Kill HCRX_HOST_FLAGS
KVM: arm64: Properly save/restore HCRX_EL2
KVM: arm64: selftest: Don't try to disable AArch64 support
KVM: arm64: Prevent userspace from disabling AArch64 support at any virtualisable EL
KVM: arm64: Force HCR_EL2.xMO to 1 at all times in VHE mode
KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()
KVM: x86/mmu: Prevent installing hugepages when mem attributes are changing
KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields
KVM: RISC-V: reset smstateen CSRs
KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload()
KVM: x86: Check that the high 32bits are clear in kvm_arch_vcpu_ioctl_run()
KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

Pull MIPS fixes from Thomas Bogendoerfer:

- Fix delayed timers

- Fix NULL pointer deref

- Fix wrong range check

* tag 'mips-fixes_6.15_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
MIPS: Fix MAX_REG_OFFSET
MIPS: CPS: Fix potential NULL pointer dereferences in cps_prepare_cpus()
MIPS: rename rollback_handler with skipover_handler
MIPS: Move r4k_wait() to .cpuidle.text section
MIPS: Fix idle VS timer enqueue

KVM x86 fixes for 6.15-rcN

- Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid causing
problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to sanitize the
VMCB as its state is undefined after SHUTDOWN, emulating INIT is the
least awful choice).

- Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
KVM doesn't goof a sanity check in the future.

- Free obsolete roots when (re)loading the MMU to fix a bug where
pre-faulting memory can get stuck due to always encountering a stale
root.

- When dumping GHCB state, use KVM's snapshot instead of the raw GHCB page
to print state, so that KVM doesn't print stale/wrong information.

- When changing memory attributes (e.g. shared <=> private), add potential
hugepage ranges to the mmu_invalidate_range_{start,end} set so that KVM
doesn't create a shared/private hugepage when the the corresponding
attributes will become mixed (the attributes are commited *after* KVM
finishes the invalidation).

- Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM has at
least one active VM. Effectively BP_SPEC_REDUCE when KVM is loaded led
to very measurable performance regressions for non-KVM workloads.

Pull x86 fix from Ingo Molnar:
"Fix a boot regression on very old x86 CPUs without CPUID support"

* tag 'x86-urgent-2025-05-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode: Consolidate the loader enablement checking

Fix MAX_REG_OFFSET to point to the last register in 'pt_regs' and not to
the marker itself, which could allow regs_get_register() to return an
invalid offset.

Fixes: 40e084a506eb ("MIPS: Add uprobes support.")
Suggested-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

KVM/arm64 fixes for 6.15, round #3

- Avoid use of uninitialized memcache pointer in user_mem_abort()

- Always set HCR_EL2.xMO bits when running in VHE, allowing interrupts
to be taken while TGE=0 and fixing an ugly bug on AmpereOne that
occurs when taking an interrupt while clearing the xMO bits
(AC03_CPU_36)

- Prevent VMMs from hiding support for AArch64 at any EL virtualized by
KVM

- Save/restore the host value for HCRX_EL2 instead of restoring an
incorrect fixed value

- Make host_stage2_set_owner_locked() check that the entire requested
range is memory rather than just the first page

Set the magic BP_SPEC_REDUCE bit to mitigate SRSO when running VMs if and
only if KVM has at least one active VM. Leaving the bit set at all times
unfortunately degrades performance by a wee bit more than expected.

Use a dedicated spinlock and counter instead of hooking virtualization
enablement, as changing the behavior of kvm.enable_virt_at_load based on
SRSO_BP_SPEC_REDUCE is painful, and has its own drawbacks, e.g. could
result in performance issues for flows that are sensitive to VM creation
latency.

Defer setting BP_SPEC_REDUCE until VMRUN is imminent to avoid impacting
performance on CPUs that aren't running VMs, e.g. if a setup is using
housekeeping CPUs. Setting BP_SPEC_REDUCE in task context, i.e. without
blasting IPIs to all CPUs, also helps avoid serializing 1<=>N transitions
without incurring a gross amount of complexity (see the Link for details
on how ugly coordinating via IPIs gets).

Link: https://lore.kernel.org/all/aBOnzNCngyS_pQIW@google.com
Fixes: 8442df2b49ed ("x86/bugs: KVM: Add support for SRSO_MSR_FIX")
Reported-by: Michael Larabel <Michael@michaellarabel.com>
Closes: https://www.phoronix.com/review/linux-615-amd-regression
Cc: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250505180300.973137-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Pull misc timers fixes from Ingo Molnar:

- Fix time keeping bugs in CLOCK_MONOTONIC_COARSE clocks

- Work around absolute relocations into vDSO code that GCC erroneously
emits in certain arm64 build environments

- Fix a false positive lockdep warning in the i8253 clocksource driver

* tag 'timers-urgent-2025-05-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()
arm64: vdso: Work around invalid absolute relocations from GCC
timekeeping: Prevent coarse clocks going backwards

Consolidate the whole logic which determines whether the microcode loader
should be enabled or not into a single function and call it everywhere.

Well, almost everywhere - not in mk_early_pgtbl_32() because there the kernel
is running without paging enabled and checking dis_ucode_ldr et al would
require physical addresses and uglification of the code.

But since this is 32-bit, the easier thing to do is to simply map the initrd
unconditionally especially since that mapping is getting removed later anyway
by zap_early_initrd_mapping() and avoid the uglification.

In doing so, address the issue of old 486er machines without CPUID
support, not booting current kernels.

[ mingo: Fix no previous prototype for ‘microcode_loader_disabled’ [-Wmissing-prototypes] ]

Fixes: 4c585af7180c1 ("x86/boot/32: Temporarily map initrd for microcode loading")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoVQ@mail.gmail.com