When copying a namespace we won't have added the new copy into the
namespace rbtree until after the copy succeeded. Calling free_mnt_ns()
will try to remove the copy from the rbtree which is invalid. Simply
free the namespace skeleton directly.
Link: https://lore.kernel.org/r/20241016-adapter-seilwinde-83c508a7bde1@brauner
Fixes: 1901c92497 ("fs: keep an index of current mount namespaces")
Tested-by: Brad Spengler <spender@grsecurity.net>
Cc: stable@vger.kernel.org # v6.11+
Reported-by: Brad Spengler <spender@grsecurity.net>
Suggested-by: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In the I/O locking code borrowed from NFS into netfslib, i_rwsem is held
locked across a buffered write - but this causes a performance regression
in cifs as it excludes buffered reads for the duration (cifs didn't use any
locking for buffered reads).
Mitigate this somewhat by downgrading the i_rwsem to a read lock across the
buffered write. This at least allows parallel reads to occur whilst
excluding other writes, DIO, truncate and setattr.
Note that this shouldn't be a problem for a buffered write as a read
through an mmap can circumvent i_rwsem anyway.
Also note that we might want to make this change in NFS also.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/1317958.1729096113@warthog.procyon.org.uk
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Trond Myklebust <trondmy@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-cifs@vger.kernel.org
cc: linux-nfs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
vsock_bpf_prot is set up at runtime. Remove the superfluous init.
No functional change intended.
Fixes: 634f1a7110 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241013-vsock-fixes-for-redir-v2-4-d6577bbfe742@rbox.co
Dequeuing via vsock_transport::read_skb() left msg_count outdated, which
then confused SOCK_SEQPACKET recv(). Decrease the counter.
Fixes: 634f1a7110 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241013-vsock-fixes-for-redir-v2-3-d6577bbfe742@rbox.co
Make sure virtio_transport_inc_rx_pkt() and virtio_transport_dec_rx_pkt()
calls are balanced (i.e. virtio_vsock_sock::rx_bytes doesn't lie) after
vsock_transport::read_skb().
While here, also inform the peer that we've freed up space and it has more
credit.
Failing to update rx_bytes after packet is dequeued leads to a warning on
SOCK_STREAM recv():
[ 233.396654] rx_queue is empty, but rx_bytes is non-zero
[ 233.396702] WARNING: CPU: 11 PID: 40601 at net/vmw_vsock/virtio_transport_common.c:589
Fixes: 634f1a7110 ("vsock: support sockmap")
Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241013-vsock-fixes-for-redir-v2-2-d6577bbfe742@rbox.co
Don't mislead the callers of bpf_{sk,msg}_redirect_{map,hash}(): make sure
to immediately and visibly fail the forwarding of unsupported af_vsock
packets.
Fixes: 634f1a7110 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241013-vsock-fixes-for-redir-v2-1-d6577bbfe742@rbox.co
Tariq Toukan says:
====================
mlx5 misc fixes 2024-10-15
This patchset provides misc bug fixes from the team to the mlx5 core and
Eth drivers.
Series generated against:
commit 174714f0e5 ("selftests: drivers: net: fix name not defined")
====================
Link: https://patch.msgid.link/20241015093208.197603-1-tariqt@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Command bitmask have a dedicated bit for MANAGE_PAGES command, this bit
isn't Initialize during command bitmask Initialization, only during
MANAGE_PAGES.
In addition, mlx5_cmd_trigger_completions() is trying to trigger
completion for MANAGE_PAGES command as well.
Hence, in case health error occurred before any MANAGE_PAGES command
have been invoke (for example, during mlx5_enable_hca()),
mlx5_cmd_trigger_completions() will try to trigger completion for
MANAGE_PAGES command, which will result in null-ptr-deref error.[1]
Fix it by Initialize command bitmask correctly.
While at it, re-write the code for better understanding.
[1]
BUG: KASAN: null-ptr-deref in mlx5_cmd_trigger_completions+0x1db/0x600 [mlx5_core]
Write of size 4 at addr 0000000000000214 by task kworker/u96:2/12078
CPU: 10 PID: 12078 Comm: kworker/u96:2 Not tainted 6.9.0-rc2_for_upstream_debug_2024_04_07_19_01 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Workqueue: mlx5_health0000:08:00.0 mlx5_fw_fatal_reporter_err_work [mlx5_core]
Call Trace:
<TASK>
dump_stack_lvl+0x7e/0xc0
kasan_report+0xb9/0xf0
kasan_check_range+0xec/0x190
mlx5_cmd_trigger_completions+0x1db/0x600 [mlx5_core]
mlx5_cmd_flush+0x94/0x240 [mlx5_core]
enter_error_state+0x6c/0xd0 [mlx5_core]
mlx5_fw_fatal_reporter_err_work+0xf3/0x480 [mlx5_core]
process_one_work+0x787/0x1490
? lockdep_hardirqs_on_prepare+0x400/0x400
? pwq_dec_nr_in_flight+0xda0/0xda0
? assign_work+0x168/0x240
worker_thread+0x586/0xd30
? rescuer_thread+0xae0/0xae0
kthread+0x2df/0x3b0
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x2d/0x70
? kthread_complete_and_exit+0x20/0x20
ret_from_fork_asm+0x11/0x20
</TASK>
Fixes: 9b98d395b8 ("net/mlx5: Start health poll at earlier stage of driver load")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Currently, mlx5 driver does not enforce vector index to be lower than
the maximum number of supported completion vectors when requesting a
new completion EQ. Thus, mlx5_comp_eqn_get() fails when trying to
acquire an IRQ with an improper vector index.
To prevent the case above, enforce that vector index value is
valid and lower than maximum in mlx5_comp_eqn_get() before handling the
request.
Fixes: f14c1a14e6 ("net/mlx5: Allocate completion EQs dynamically")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The HWS BWC API uses one lock per queue and usually acquires one of
them, except when doing changes which require locking all queues in
order. Naturally, lockdep isn't too happy about acquiring the same lock
class multiple times, so inform it that each queue lock is a different
class to avoid false positives.
Fixes: 2ca62599aa ("net/mlx5: HWS, added send engine and context handling")
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
hws_send_queues_bwc_locks_destroy destroyed more queue locks than
allocated, leading to memory corruption (occasionally) and warnings such
as DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock)) in __mutex_destroy because
sometimes, the 'mutex' being destroyed was random memory.
The severity of this problem is proportional to the number of queues
configured because the code overreaches beyond the end of the
bwc_send_queue_locks array by 2x its length.
Fix that by using the correct number of bwc queues.
Fixes: 2ca62599aa ("net/mlx5: HWS, added send engine and context handling")
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Fix error flow bug that could lead to double free of a buffer
during a failure to calculate a suitable definer layout.
Fixes: 74a778b4a6 ("net/mlx5: HWS, added definers handling")
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Itamar Gozlan <igozlan@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Removed wrong access to the num_of_rules field of the matcher.
This is a usual u32 variable, but the access was as if it was atomic.
This fixes the following CI warnings:
mlx5hws_bwc.c:708:17: warning: large atomic operation may incur significant performance penalty;
the access size (4 bytes) exceeds the max lock-free size (0 bytes) [-Watomic-alignment]
Fixes: 510f9f61a1 ("net/mlx5: HWS, added API and enabled HWS support")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409291101.6NdtMFVC-lkp@intel.com/
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Itamar Gozlan <igozlan@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The loop responsible for allocating up to MTK_FQ_DMA_LENGTH buffers must
only touch as many descriptors, otherwise it ends up corrupting unrelated
memory. Fix the loop iteration count accordingly.
Fixes: c57e558194 ("net: ethernet: mtk_eth_soc: handle dma buffer size soc specific")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241015081755.31060-1-nbd@nbd.name
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Andrew and Nikolay reported connectivity issues with Cilium's service
load-balancing in case of vmxnet3.
If a BPF program for native XDP adds an encapsulation header such as
IPIP and transmits the packet out the same interface, then in case
of vmxnet3 a corrupted packet is being sent and subsequently dropped
on the path.
vmxnet3_xdp_xmit_frame() which is called e.g. via vmxnet3_run_xdp()
through vmxnet3_xdp_xmit_back() calculates an incorrect DMA address:
page = virt_to_page(xdpf->data);
tbi->dma_addr = page_pool_get_dma_addr(page) +
VMXNET3_XDP_HEADROOM;
dma_sync_single_for_device(&adapter->pdev->dev,
tbi->dma_addr, buf_size,
DMA_TO_DEVICE);
The above assumes a fixed offset (VMXNET3_XDP_HEADROOM), but the XDP
BPF program could have moved xdp->data. While the passed buf_size is
correct (xdpf->len), the dma_addr needs to have a dynamic offset which
can be calculated as xdpf->data - (void *)xdpf, that is, xdp->data -
xdp->data_hard_start.
Fixes: 54f00cce11 ("vmxnet3: Add XDP support.")
Reported-by: Andrew Sauber <andrew.sauber@isovalent.com>
Reported-by: Nikolay Nikolaev <nikolay.nikolaev@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Nikolay Nikolaev <nikolay.nikolaev@isovalent.com>
Acked-by: Anton Protopopov <aspsk@isovalent.com>
Cc: William Tu <witu@nvidia.com>
Cc: Ronak Doshi <ronak.doshi@broadcom.com>
Link: https://patch.msgid.link/a0888656d7f09028f9984498cc698bb5364d89fc.1728931137.git.daniel@iogearbox.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
kvm_vgic_map_resources() prematurely marks the distributor as 'ready',
potentially allowing vCPUs to enter the guest before the distributor's
MMIO registration has been made visible.
Plug the race by marking the distributor as ready only after MMIO
registration is completed. Rely on the implied ordering of
synchronize_srcu() to ensure the MMIO registration is visible before
vgic_dist::ready. This also means that writers to vgic_dist::ready are
now serialized by the slots_lock, which was effectively the case already
as all writers held the slots_lock in addition to the config_lock.
Fixes: 59112e9c39 ("KVM: arm64: vgic: Fix a circular locking issue")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241017001947.2707312-3-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
KVM commits to a particular sizing of SPIs when the vgic is initialized,
which is before the point a vgic becomes ready. On top of that, KVM
supplies a default amount of SPIs should userspace not explicitly
configure this.
As such, the check for vgic_ready() in the handling of
KVM_DEV_ARM_VGIC_GRP_NR_IRQS is completely wrong, and testing if nr_spis
is nonzero is sufficient for preventing userspace from playing games
with us.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241017001947.2707312-2-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
Our idmap is becoming too big, to the point where it doesn't fit in
a 4kB page anymore.
There are some low-hanging fruits though, such as the el2_init_state
horror that is expanded 3 times in the kernel. Let's at least limit
ourselves to two copies, which makes the kernel link again.
At some point, we'll have to have a better way of doing this.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241009204903.GA3353168@thelio-3990X
Conflicts:
kernel/sched/ext.c
There's a context conflict between this upstream commit:
3fdb9ebcec sched_ext: Start schedulers with consistent p->scx.slice values
... and this fix in sched/urgent:
98442f0ccd sched: Fix delayed_dequeue vs switched_from_fair()
Resolve it.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fixes for v6.12
Display:
- move CRTC resource assignment to atomic_check otherwise to make
consecutive calls to atomic_check() consistent
- fix rounding / sign-extension issues with pclk calculation in
case of DSC
- cleanups to drop incorrect null checks in dpu snapshots
- fix to use kvzalloc in dpu snapshot to avoid allocation issues
in heavily loaded system cases
- Fix to not program merge_3d block if dual LM is not being used
- Fix to not flush merge_3d block if its not enabled otherwise
this leads to false timeouts
GPU:
- a7xx: add a fence wait before SMMU table update
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/CAF6AEGsp3Zbd_H3FhHdRz9yCYA4wxX4SenpYRSk=Mx2d8GMSuQ@mail.gmail.com
lru_gen_shrink_node() unconditionally clears kswapd_failures, which can
prevent kswapd from sleeping and cause 100% kswapd cpu usage even when
kswapd repeatedly fails to make progress in reclaim.
Only clear kswap_failures in lru_gen_shrink_node() if reclaim makes some
progress, similar to shrink_node().
I happened to run into this problem in one of my tests recently. It
requires a combination of several conditions: The allocator needs to
allocate a right amount of pages such that it can wake up kswapd
without itself being OOM killed; there is no memory for kswapd to
reclaim (My test disables swap and cleans page cache first); no other
process frees enough memory at the same time.
Link: https://lkml.kernel.org/r/20241014221211.832591-1-weixugc@google.com
Fixes: e4dde56cd2 ("mm: multi-gen LRU: per-node lru_gen_folio lists")
Signed-off-by: Wei Xu <weixugc@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Jan Alexander Steffens <heftig@archlinux.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
I got a bad pud error and lost a 1GB HugeTLB when calling swapoff. The
problem can be reproduced by the following steps:
1. Allocate an anonymous 1GB HugeTLB and some other anonymous memory.
2. Swapout the above anonymous memory.
3. run swapoff and we will get a bad pud error in kernel message:
mm/pgtable-generic.c:42: bad pud 00000000743d215d(84000001400000e7)
We can tell that pud_clear_bad is called by pud_none_or_clear_bad in
unuse_pud_range() by ftrace. And therefore the HugeTLB pages will never
be freed because we lost it from page table. We can skip HugeTLB pages
for unuse_vma to fix it.
Link: https://lkml.kernel.org/r/20241015014521.570237-1-liushixin2@huawei.com
Fixes: 0fe6e20b9c ("hugetlb, rmap: add reverse mapping for hugepage")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The mount option of tmpfs should be huge=advise, not madvise which is not
supported and may mislead the users.
Link: https://lkml.kernel.org/r/20241015020257.139235-1-sunnanyong@huawei.com
Fixes: 1b03d0d558 ("selftests/vm: add thp collapse file and tmpfs testing")
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add myself as a reviewer for memory mapping / VMA code. I will probably
only reply to patches sporadically, but hopefully this will help me keep
up with changes that look interesting security-wise.
Link: https://lkml.kernel.org/r/20241014-maintainers-mmap-reviewer-v1-1-50dce0514752@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A report [1] was uploaded from syzbot.
In the previous commit 862590ac37 ("mm: swap: allow cache reclaim to
skip slot cache"), the __try_to_reclaim_swap() function reads offset and
folio->entry from folio without folio_lock protection.
In the currently reported KCSAN log, it is assumed that the actual
data-race will not occur because the calltrace that does WRITE already
obtains the folio_lock and then writes.
However, the existing __try_to_reclaim_swap() function was already
implemented to perform reads under folio_lock protection [1], and there is
a risk of a data-race occurring through a function other than the one
shown in the KCSAN log.
Therefore, I think it is appropriate to change
read operations for folio to be performed under folio_lock.
[1]
==================================================================
BUG: KCSAN: data-race in __delete_from_swap_cache / __try_to_reclaim_swap
write to 0xffffea0004c90328 of 8 bytes by task 5186 on cpu 0:
__delete_from_swap_cache+0x1f0/0x290 mm/swap_state.c:163
delete_from_swap_cache+0x72/0xe0 mm/swap_state.c:243
folio_free_swap+0x1d8/0x1f0 mm/swapfile.c:1850
free_swap_cache mm/swap_state.c:293 [inline]
free_pages_and_swap_cache+0x1fc/0x410 mm/swap_state.c:325
__tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
tlb_flush_mmu+0x2cf/0x440 mm/mmu_gather.c:373
zap_pte_range mm/memory.c:1700 [inline]
zap_pmd_range mm/memory.c:1739 [inline]
zap_pud_range mm/memory.c:1768 [inline]
zap_p4d_range mm/memory.c:1789 [inline]
unmap_page_range+0x1f3c/0x22d0 mm/memory.c:1810
unmap_single_vma+0x142/0x1d0 mm/memory.c:1856
unmap_vmas+0x18d/0x2b0 mm/memory.c:1900
exit_mmap+0x18a/0x690 mm/mmap.c:1864
__mmput+0x28/0x1b0 kernel/fork.c:1347
mmput+0x4c/0x60 kernel/fork.c:1369
exit_mm+0xe4/0x190 kernel/exit.c:571
do_exit+0x55e/0x17f0 kernel/exit.c:926
do_group_exit+0x102/0x150 kernel/exit.c:1088
get_signal+0xf2a/0x1070 kernel/signal.c:2917
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
read to 0xffffea0004c90328 of 8 bytes by task 5189 on cpu 1:
__try_to_reclaim_swap+0x9d/0x510 mm/swapfile.c:198
free_swap_and_cache_nr+0x45d/0x8a0 mm/swapfile.c:1915
zap_pte_range mm/memory.c:1656 [inline]
zap_pmd_range mm/memory.c:1739 [inline]
zap_pud_range mm/memory.c:1768 [inline]
zap_p4d_range mm/memory.c:1789 [inline]
unmap_page_range+0xcf8/0x22d0 mm/memory.c:1810
unmap_single_vma+0x142/0x1d0 mm/memory.c:1856
unmap_vmas+0x18d/0x2b0 mm/memory.c:1900
exit_mmap+0x18a/0x690 mm/mmap.c:1864
__mmput+0x28/0x1b0 kernel/fork.c:1347
mmput+0x4c/0x60 kernel/fork.c:1369
exit_mm+0xe4/0x190 kernel/exit.c:571
do_exit+0x55e/0x17f0 kernel/exit.c:926
__do_sys_exit kernel/exit.c:1055 [inline]
__se_sys_exit kernel/exit.c:1053 [inline]
__x64_sys_exit+0x1f/0x20 kernel/exit.c:1053
x64_sys_call+0x2d46/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:61
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
value changed: 0x0000000000000242 -> 0x0000000000000000
Link: https://lkml.kernel.org/r/20241007070623.23340-1-aha310510@gmail.com
Reported-by: syzbot+fa43f1b63e3aa6f66329@syzkaller.appspotmail.com
Fixes: 862590ac37 ("mm: swap: allow cache reclaim to skip slot cache")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Khugepaged already supports collapsing file large folios (including shmem
mTHP) by commit 7de856ffd0 ("mm: khugepaged: support shmem mTHP
collapse"), and the control parameters in khugepaged:
'khugepaged_max_ptes_swap' and 'khugepaged_max_ptes_none', still compare
based on PTE granularity to determine whether a file collapse is needed.
However, the statistics for 'present' and 'swap' in
hpage_collapse_scan_file() do not take into account the large folios,
which may lead to incorrect judgments regarding the
khugepaged_max_ptes_swap/none parameters, resulting in unnecessary file
collapses.
To fix this issue, take into account the large folios' statistics for
'present' and 'swap' variables in the hpage_collapse_scan_file().
Link: https://lkml.kernel.org/r/c76305d96d12d030a1a346b50503d148364246d2.1728901391.git.baolin.wang@linux.alibaba.com
Fixes: 7de856ffd0 ("mm: khugepaged: support shmem mTHP collapse")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add links to the Bugzilla component that's used to track KASAN and KCOV
issues.
Link: https://lkml.kernel.org/r/20241012225524.117871-1-andrey.konovalov@linux.dev
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We (or rather, readahead logic :) ) might be allocating a THP in the
pagecache and then try mapping it into a process that explicitly disabled
THP: we might end up installing PMD mappings.
This is a problem for s390x KVM, which explicitly remaps all PMD-mapped
THPs to be PTE-mapped in s390_enable_sie()->thp_split_mm(), before
starting the VM.
For example, starting a VM backed on a file system with large folios
supported makes the VM crash when the VM tries accessing such a mapping
using KVM.
Is it also a problem when the HW disabled THP using
TRANSPARENT_HUGEPAGE_UNSUPPORTED? At least on x86 this would be the case
without X86_FEATURE_PSE.
In the future, we might be able to do better on s390x and only disallow
PMD mappings -- what s390x and likely TRANSPARENT_HUGEPAGE_UNSUPPORTED
really wants. For now, fix it by essentially performing the same check as
would be done in __thp_vma_allowable_orders() or in shmem code, where this
works as expected, and disallow PMD mappings, making us fallback to PTE
mappings.
Link: https://lkml.kernel.org/r/20241011102445.934409-3-david@redhat.com
Fixes: 793917d997 ("mm/readahead: Add large folio readahead")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Leo Fu <bfu@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: don't install PMD mappings when THPs are disabled by the
hw/process/vma".
During testing, it was found that we can get PMD mappings in processes
where THP (and more precisely, PMD mappings) are supposed to be disabled.
While it works as expected for anon+shmem, the pagecache is the
problematic bit.
For s390 KVM this currently means that a VM backed by a file located on
filesystem with large folio support can crash when KVM tries accessing the
problematic page, because the readahead logic might decide to use a
PMD-sized THP and faulting it into the page tables will install a PMD
mapping, something that s390 KVM cannot tolerate.
This might also be a problem with HW that does not support PMD mappings,
but I did not try reproducing it.
Fix it by respecting the ways to disable THPs when deciding whether we can
install a PMD mapping. khugepaged should already be taking care of not
collapsing if THPs are effectively disabled for the hw/process/vma.
This patch (of 2):
Add vma_thp_disabled() and thp_disabled_by_hw() helpers to be shared by
shmem_allowable_huge_orders() and __thp_vma_allowable_orders().
[david@redhat.com: rename to vma_thp_disabled(), split out thp_disabled_by_hw() ]
Link: https://lkml.kernel.org/r/20241011102445.934409-2-david@redhat.com
Fixes: 793917d997 ("mm/readahead: Add large folio readahead")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Leo Fu <bfu@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Boqiao Fu <bfu@redhat.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Docs/damon/maintainer-profile: a couple of minor hotfixes".
DAMON maintainer-profile.rst file patches[1] that were merged into the
v6.12-rc1 have a couple of minor mistakes. Fix those.
[1] https://lore.kernel.org/20240826015741.80707-1-sj@kernel.org
This patch (of 2):
Links to external web pages on DAMON's maintainer-profile.rst are missing
'_' suffixes. As a result, rendered document is having only verbose URLs
that cannot be clicked. Fix those.
Also, update the link texts for git trees to contain the names of the
trees, for better readability and avoiding below Sphinx warning.
maintainer-profile.rst:4: WARNING: Duplicate explicit target name: "tree".
Link: https://lkml.kernel.org/r/20241011170154.70651-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20241011170154.70651-2-sj@kernel.org
Fixes: 2e9b3d6e2e ("Docs/damon/maintainer-profile: add links in place")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It is possible for a bulk operation (MA_STATE_BULK is set) to enter the
new_end < mt_min_slots[type] case and set wr_rebalance as a store type.
This is incorrect as bulk stores do not rebalance per write, but rather
after the all of the writes are done through the mas_bulk_rebalance()
path. Therefore, add a check to make sure MA_STATE_BULK is not set before
we return wr_rebalance as the store type.
Also add a test to make sure wr_rebalance is never the store type when
doing bulk operations via mas_expected_entries()
This is a hotfix for this rc however it has no userspace effects as there
are no users of the bulk insertion mode.
Link: https://lkml.kernel.org/r/20241011214451.7286-1-sidhartha.kumar@oracle.com
Fixes: 5d659bbb52 ("maple_tree: introduce mas_wr_store_type()")
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Sidhartha <sidhartha.kumar@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The "addr" and "is_shmem" arguments have different order in TP_PROTO and
TP_ARGS. This resulted in the incorrect trace result:
text-hugepage-644429 [276] 392092.878683: mm_khugepaged_collapse_file:
mm=0xffff20025d52c440, hpage_pfn=0x200678c00, index=512, addr=1, is_shmem=0,
filename=text-hugepage, nr=512, result=failed
The value of "addr" is wrong because it was treated as bool value, the
type of is_shmem.
Fix the order in TP_PROTO to keep "addr" is before "is_shmem" since the
original patch review suggested this order to achieve best packing.
And use "lx" for "addr" instead of "ld" in TP_printk because address is
typically shown in hex.
After the fix, the trace result looks correct:
text-hugepage-7291 [004] 128.627251: mm_khugepaged_collapse_file:
mm=0xffff0001328f9500, hpage_pfn=0x20016ea00, index=512, addr=0x400000,
is_shmem=0, filename=text-hugepage, nr=512, result=failed
Link: https://lkml.kernel.org/r/20241012011702.1084846-1-yang@os.amperecomputing.com
Fixes: 4c9473e87e ("mm/khugepaged: add tracepoint to collapse_file()")
Signed-off-by: Yang Shi <yang@os.amperecomputing.com>
Cc: Gautam Menghani <gautammenghani201@gmail.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org> [6.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When can_swapin_thp() is unused, it prevents kernel builds with clang,
`make W=1` and CONFIG_WERROR=y:
mm/memory.c:4184:20: error: unused function 'can_swapin_thp' [-Werror,-Wunused-function]
Fix this by removing the unused stub.
See also commit 6863f5643d ("kbuild: allow Clang to find unused static
inline functions for W=1 build").
Link: https://lkml.kernel.org/r/20241008191329.2332346-1-andriy.shevchenko@linux.intel.com
Fixes: 242d12c981 ("mm: support large folios swap-in for sync io devices")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Barry Song <baohua@kernel.org>
Cc: Bill Wendling <morbo@google.com>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Map my outdated addresses within mailmap.
Link: https://lkml.kernel.org/r/20241009144934.43027-1-andybnac@gmail.com
Signed-off-by: Andy Chiu <andybnac@gmail.com>
Cc: Greentime Hu <greentime.hu@sifive.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Leon Chien <leonchien@synology.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add myself and Liam as co-maintainers of the memory mapping and VMA code
alongside Andrew as we are heavily involved in its implementation and
maintenance.
Link: https://lkml.kernel.org/r/20241009201032.6130-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show show_smap_vma_flags() has been a using misspelled initializer in
mnemonics[] - it needed to initialize 2 element array of char and it used
NUL-padded 2 character string literals (i.e. 3-element initializer).
This has been spotted by gcc-15[*]; prior to that gcc quietly dropped the
3rd eleemnt of initializers. To fix this we are increasing the size of
mnemonics[] (from mnemonics[BITS_PER_LONG][2] to
mnemonics[BITS_PER_LONG][3]) to accomodate the NUL-padded string literals.
This also helps us in simplyfying the logic for printing of the flags as
instead of printing each character from the mnemonics[], we can just print
the mnemonics[] using seq_printf.
[*]: fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
917 | [0 ... (BITS_PER_LONG-1)] = "??",
| ^~~~
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
fs/proc/task_mmu.c:917:49: error: initializer-string for array of `char' is too long [-Werror=unterminate d-string-initialization]
...
Stephen pointed out:
: The C standard explicitly allows for a string initializer to be too long
: due to the NUL byte at the end ... so this warning may be overzealous.
but let's make the warning go away anwyay.
Link: https://lkml.kernel.org/r/20241005063700.2241027-1-brahmajit.xyz@gmail.com
Link: https://lkml.kernel.org/r/20241003093040.47c08382@canb.auug.org.au
Signed-off-by: Brahmajit Das <brahmajit.xyz@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In mremap(), move_page_tables() looks at the type of the PMD entry and the
specified address range to figure out by which method the next chunk of
page table entries should be moved.
At that point, the mmap_lock is held in write mode, but no rmap locks are
held yet. For PMD entries that point to page tables and are fully covered
by the source address range, move_pgt_entry(NORMAL_PMD, ...) is called,
which first takes rmap locks, then does move_normal_pmd().
move_normal_pmd() takes the necessary page table locks at source and
destination, then moves an entire page table from the source to the
destination.
The problem is: The rmap locks, which protect against concurrent page
table removal by retract_page_tables() in the THP code, are only taken
after the PMD entry has been read and it has been decided how to move it.
So we can race as follows (with two processes that have mappings of the
same tmpfs file that is stored on a tmpfs mount with huge=advise); note
that process A accesses page tables through the MM while process B does it
through the file rmap:
process A process B
========= =========
mremap
mremap_to
move_vma
move_page_tables
get_old_pmd
alloc_new_pmd
*** PREEMPT ***
madvise(MADV_COLLAPSE)
do_madvise
madvise_walk_vmas
madvise_vma_behavior
madvise_collapse
hpage_collapse_scan_file
collapse_file
retract_page_tables
i_mmap_lock_read(mapping)
pmdp_collapse_flush
i_mmap_unlock_read(mapping)
move_pgt_entry(NORMAL_PMD, ...)
take_rmap_locks
move_normal_pmd
drop_rmap_locks
When this happens, move_normal_pmd() can end up creating bogus PMD entries
in the line `pmd_populate(mm, new_pmd, pmd_pgtable(pmd))`. The effect
depends on arch-specific and machine-specific details; on x86, you can end
up with physical page 0 mapped as a page table, which is likely
exploitable for user->kernel privilege escalation.
Fix the race by letting process B recheck that the PMD still points to a
page table after the rmap locks have been taken. Otherwise, we bail and
let the caller fall back to the PTE-level copying path, which will then
bail immediately at the pmd_none() check.
Bug reachability: Reaching this bug requires that you can create
shmem/file THP mappings - anonymous THP uses different code that doesn't
zap stuff under rmap locks. File THP is gated on an experimental config
flag (CONFIG_READ_ONLY_THP_FOR_FS), so on normal distro kernels you need
shmem THP to hit this bug. As far as I know, getting shmem THP normally
requires that you can mount your own tmpfs with the right mount flags,
which would require creating your own user+mount namespace; though I don't
know if some distros maybe enable shmem THP by default or something like
that.
Bug impact: This issue can likely be used for user->kernel privilege
escalation when it is reachable.
Link: https://lkml.kernel.org/r/20241007-move_normal_pmd-vs-collapse-fix-2-v1-1-5ead9631f2ea@google.com
Fixes: 1d65b771bc ("mm/khugepaged: retract_page_tables() without mmap or vma lock")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Co-developed-by: David Hildenbrand <david@redhat.com>
Closes: https://project-zero.issues.chromium.org/371047675
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Arnd reported a build failure due to the BUILD_BUG_ON() statement in
alloc_kmem_cache_cpus(). The test
PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu)
The factors that increase the right side of the equation:
- PAGE_SIZE > 4KiB increases KMALLOC_SHIFT_HIGH
- For the local_lock_t in kmem_cache_cpu:
- PREEMPT_RT adds an actual lock.
- LOCKDEP increases the size of the lock.
- LOCK_STAT adds additional bytes plus padding to the lockdep
structure.
The net difference with and without PREEMPT_RT is 88 bytes for the
lock_lock_t, 96 bytes for kmem_cache_cpu due to additional padding. This
is enough to exceed the 80KiB limit with 16KiB page size - the 8KiB page
size is fine.
Increase PERCPU_DYNAMIC_SIZE_SHIFT to 13 on configs with PAGE_SIZE larger
than 4KiB and LOCKDEP enabled.
Link: https://lkml.kernel.org/r/20241007143049.gyMpEu89@linutronix.de
Fixes: d8fccd9ca5 ("arm64: Allow to enable PREEMPT_RT.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410020326.iaZIteIx-lkp@intel.com/
Reported-by: Arnd Bergmann <arnd@kernel.org>
Closes: https://lore.kernel.org/20241004095702.637528-1-arnd@kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On Android with arm, there is some synchronization needed to avoid a
deadlock when forking after pthread_create.
Link: https://lkml.kernel.org/r/20241003211716.371786-3-edliaw@google.com
Fixes: cff2945827 ("selftests/mm: extend and rename uffd pagemap test")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "selftests/mm: fix deadlock after pthread_create".
On Android arm, pthread_create followed by a fork caused a deadlock in the
case where the fork required work to be completed by the created thread.
Update the synchronization primitive to use pthread_barrier instead of
atomic_bool.
Apply the same fix to the wp-fork-with-event test.
This patch (of 2):
Swap synchronization primitive with pthread_barrier, so that stdatomic.h
does not need to be included.
The synchronization is needed on Android ARM64; we see a deadlock with
pthread_create when the parent thread races forward before the child has a
chance to start doing work.
Link: https://lkml.kernel.org/r/20241003211716.371786-1-edliaw@google.com
Link: https://lkml.kernel.org/r/20241003211716.371786-2-edliaw@google.com
Fixes: cff2945827 ("selftests/mm: extend and rename uffd pagemap test")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Syzbot reported that a task hang occurs in vcs_open() during a fuzzing
test for nilfs2.
The root cause of this problem is that in nilfs_find_entry(), which
searches for directory entries, ignores errors when loading a directory
page/folio via nilfs_get_folio() fails.
If the filesystem images is corrupted, and the i_size of the directory
inode is large, and the directory page/folio is successfully read but
fails the sanity check, for example when it is zero-filled,
nilfs_check_folio() may continue to spit out error messages in bursts.
Fix this issue by propagating the error to the callers when loading a
page/folio fails in nilfs_find_entry().
The current interface of nilfs_find_entry() and its callers is outdated
and cannot propagate error codes such as -EIO and -ENOMEM returned via
nilfs_find_entry(), so fix it together.
Link: https://lkml.kernel.org/r/20241004033640.6841-1-konishi.ryusuke@gmail.com
Fixes: 2ba466d74e ("nilfs2: directory entry operations")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: Lizhi Xu <lizhi.xu@windriver.com>
Closes: https://lkml.kernel.org/r/20240927013806.3577931-1-lizhi.xu@windriver.com
Reported-by: syzbot+8a192e8d090fa9a31135@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a192e8d090fa9a31135
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit f8d112a4e6 ("mm/mmap: avoid zeroing vma tree in mmap_region()")
changed how error handling is performed in mmap_region().
The error value defaults to -ENOMEM, but then gets reassigned immediately
to the result of vms_gather_munmap_vmas() if we are performing a MAP_FIXED
mapping over existing VMAs (and thus unmapping them).
This overwrites the error value, potentially clearing it.
After this, we invoke may_expand_vm() and possibly vm_area_alloc(), and
check to see if they failed. If they do so, then we perform error-handling
logic, but importantly, we do NOT update the error code.
This means that, if vms_gather_munmap_vmas() succeeds, but one of these
calls does not, the function will return indicating no error, but rather an
address value of zero, which is entirely incorrect.
Correct this and avoid future confusion by strictly setting error on each
and every occasion we jump to the error handling logic, and set the error
code immediately prior to doing so.
This way we can see at a glance that the error code is always correct.
Many thanks to Vegard Nossum who spotted this issue in discussion around
this problem.
Link: https://lkml.kernel.org/r/20241002073932.13482-1-lorenzo.stoakes@oracle.com
Fixes: f8d112a4e6 ("mm/mmap: avoid zeroing vma tree in mmap_region()")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Suggested-by: Vegard Nossum <vegard.nossum@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
