Use per-vma locking in the shrinker's callback when reclaiming pages,
similar to the page installation logic. This minimizes contention with
unrelated vmas improving performance. The mmap_sem is still acquired if
the per-vma lock cannot be obtained.
Cc: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-10-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of always overriding errors with -ENOMEM, propagate the specific
error code returned by vm_insert_page(). This allows for more accurate
error logs and handling.
Cc: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-9-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use per-vma locking for concurrent page installations, this minimizes
contention with unrelated vmas improving performance. The mmap_lock is
still acquired when needed though, e.g. before get_user_pages_remote().
Many thanks to Barry Song who posted a similar approach [1].
Link: https://lore.kernel.org/all/20240902225009.34576-1-21cnbao@gmail.com/ [1]
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-8-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The alloc->buffer field in struct binder_alloc stores the starting
address of the mapped vma, rename this field to alloc->vm_start to
better reflect its purpose. It also avoids confusion with the binder
buffer concept, e.g. transaction->buffer.
No functional changes in this patch.
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-7-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is unsafe to use alloc->vma outside of the mmap_sem. Instead, add a
new boolean alloc->mapped to save the vma state (mapped or unmmaped) and
use this as a replacement for alloc->vma to validate several paths.
Using the alloc->vma caused several performance and security issues in
the past. Now that it has been replaced with either vm_lookup() or the
alloc->mapped state, we can finally remove it.
Cc: Minchan Kim <minchan@kernel.org>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-6-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of pre-allocating an entire array of struct binder_lru_page in
alloc->pages, install the shrinker metadata under page->private. This
ensures the memory is allocated and released as needed alongside pages.
By converting the alloc->pages[] into an array of struct page pointers,
we can access these pages directly and only reference the shrinker
metadata where it's being used (e.g. inside the shrinker's callback).
Rename struct binder_lru_page to struct binder_shrinker_mdata to better
reflect its purpose. Add convenience functions that wrap the allocation
and freeing of pages along with their shrinker metadata.
Note I've reworked this patch to avoid using page->lru and page->index
directly, as Matthew pointed out that these are being removed [1].
Link: https://lore.kernel.org/all/ZzziucEm3np6e7a0@casper.infradead.org/ [1]
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-5-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The numa node id for binder pages is currently being derived from the
lru entry under struct binder_lru_page. However, this object doesn't
reflect the node id of the struct page items allocated separately.
Instead, select the correct node id from the page itself. This was made
possible since commit 0a97c01cd2 ("list_lru: allow explicit memcg and
NUMA node selection").
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-4-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Allow multiple callers to install pages simultaneously by switching the
mmap_sem from write-mode to read-mode. Races to the same PTE are handled
using get_user_pages_remote() to retrieve the already installed page.
This method significantly reduces contention in the mmap semaphore.
To ensure safety, vma_lookup() is used (instead of alloc->vma) to avoid
operating on an isolated VMA. In addition, zap_page_range_single() is
called under the alloc->mutex to avoid racing with the shrinker.
Many thanks to Barry Song who posted a similar approach [1].
Link: https://lore.kernel.org/all/20240902225009.34576-1-21cnbao@gmail.com/ [1]
Cc: David Hildenbrand <david@redhat.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-3-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 7710e2cca3.
In preparation for concurrent page installations, restore the original
alloc->mutex which will serialize zap_page_range_single() against page
installations in subsequent patches (instead of the mmap_sem).
Resolved trivial conflicts with commit 2c10a20f5e ("binder_alloc: Fix
sleeping function called from invalid context") and commit da0c02516c
("mm/list_lru: simplify the list_lru walk callback function").
Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now isolation no longer takes the list_lru global node lock, only use the
per-cgroup lock instead. And this lock is inside the list_lru_one being
walked, no longer needed to pass the lock explicitly.
Link: https://lkml.kernel.org/r/20241104175257.60853-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, every list_lru has a per-node lock that protects adding,
deletion, isolation, and reparenting of all list_lru_one instances
belonging to this list_lru on this node. This lock contention is heavy
when multiple cgroups modify the same list_lru.
This lock can be split into per-cgroup scope to reduce contention.
To achieve this, we need a stable list_lru_one for every cgroup. This
commit adds a lock to each list_lru_one and introduced a helper function
lock_list_lru_of_memcg, making it possible to pin the list_lru of a memcg.
Then reworked the reparenting process.
Reparenting will switch the list_lru_one instances one by one. By locking
each instance and marking it dead using the nr_items counter, reparenting
ensures that all items in the corresponding cgroup (on-list or not,
because items have a stable cgroup, see below) will see the list_lru_one
switch synchronously.
Objcg reparent is also moved after list_lru reparent so items will have a
stable mem cgroup until all list_lru_one instances are drained.
The only caller that doesn't work the *_obj interfaces are direct calls to
list_lru_{add,del}. But it's only used by zswap and that's also based on
objcg, so it's fine.
This also changes the bahaviour of the isolation function when LRU_RETRY
or LRU_REMOVED_RETRY is returned, because now releasing the lock could
unblock reparenting and free the list_lru_one, isolation function will
have to return withoug re-lock the lru.
prepare() {
mkdir /tmp/test-fs
modprobe brd rd_nr=1 rd_size=33554432
mkfs.xfs -f /dev/ram0
mount -t xfs /dev/ram0 /tmp/test-fs
for i in $(seq 1 512); do
mkdir "/tmp/test-fs/$i"
for j in $(seq 1 10240); do
echo TEST-CONTENT > "/tmp/test-fs/$i/$j"
done &
done; wait
}
do_test() {
read_worker() {
sleep 1
tar -cv "$1" &>/dev/null
}
read_in_all() {
cd "/tmp/test-fs" && ls
for i in $(seq 1 512); do
(exec sh -c 'echo "$PPID"') > "/sys/fs/cgroup/benchmark/$i/cgroup.procs"
read_worker "$i" &
done; wait
}
for i in $(seq 1 512); do
mkdir -p "/sys/fs/cgroup/benchmark/$i"
done
echo +memory > /sys/fs/cgroup/benchmark/cgroup.subtree_control
echo 512M > /sys/fs/cgroup/benchmark/memory.max
echo 3 > /proc/sys/vm/drop_caches
time read_in_all
}
Above script simulates compression of small files in multiple cgroups
with memory pressure. Run prepare() then do_test for 6 times:
Before:
real 0m7.762s user 0m11.340s sys 3m11.224s
real 0m8.123s user 0m11.548s sys 3m2.549s
real 0m7.736s user 0m11.515s sys 3m11.171s
real 0m8.539s user 0m11.508s sys 3m7.618s
real 0m7.928s user 0m11.349s sys 3m13.063s
real 0m8.105s user 0m11.128s sys 3m14.313s
After this commit (about ~15% faster):
real 0m6.953s user 0m11.327s sys 2m42.912s
real 0m7.453s user 0m11.343s sys 2m51.942s
real 0m6.916s user 0m11.269s sys 2m43.957s
real 0m6.894s user 0m11.528s sys 2m45.346s
real 0m6.911s user 0m11.095s sys 2m43.168s
real 0m6.773s user 0m11.518s sys 2m40.774s
Link: https://lkml.kernel.org/r/20241104175257.60853-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Variable page_addr is being assigned a value that is never read. The
variable is redundant and can be removed.
Cleans up clang scan build warning:
warning: Value stored to 'page_addr' is never read [deadcode.DeadStores]
Signed-off-by: Colin Ian King <colin.i.king@intel.com>
Fixes: 162c797314 ("binder: avoid user addresses in debug logs")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312060851.cudv98wG-lkp@intel.com/
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240307221505.101431-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is the big set of char/misc and other driver subsystem changes for
6.8-rc1. Lots of stuff in here, but first off, you will get a merge
conflict in drivers/android/binder_alloc.c when merging this tree due to
changing coming in through the -mm tree.
The resolution of the merge issue can be found here:
https://lore.kernel.org/r/20231207134213.25631ae9@canb.auug.org.au
or in a simpler patch form in that thread:
https://lore.kernel.org/r/ZXHzooF07LfQQYiE@google.com
If there are issues with the merge of this file, please let me know.
Other than lots of binder driver changes (as you can see by the merge
conflicts) included in here are:
- lots of iio driver updates and additions
- spmi driver updates
- eeprom driver updates
- firmware driver updates
- ocxl driver updates
- mhi driver updates
- w1 driver updates
- nvmem driver updates
- coresight driver updates
- platform driver remove callback api changes
- tags.sh script updates
- bus_type constant marking cleanups
- lots of other small driver updates
All of these have been in linux-next for a while with no reported issues
(other than the binder merge conflict.)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc and other driver updates from Greg KH:
"Here is the big set of char/misc and other driver subsystem changes
for 6.8-rc1.
Other than lots of binder driver changes (as you can see by the merge
conflicts) included in here are:
- lots of iio driver updates and additions
- spmi driver updates
- eeprom driver updates
- firmware driver updates
- ocxl driver updates
- mhi driver updates
- w1 driver updates
- nvmem driver updates
- coresight driver updates
- platform driver remove callback api changes
- tags.sh script updates
- bus_type constant marking cleanups
- lots of other small driver updates
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (341 commits)
android: removed duplicate linux/errno
uio: Fix use-after-free in uio_open
drivers: soc: xilinx: add check for platform
firmware: xilinx: Export function to use in other module
scripts/tags.sh: remove find_sources
scripts/tags.sh: use -n to test archinclude
scripts/tags.sh: add local annotation
scripts/tags.sh: use more portable -path instead of -wholename
scripts/tags.sh: Update comment (addition of gtags)
firmware: zynqmp: Convert to platform remove callback returning void
firmware: turris-mox-rwtm: Convert to platform remove callback returning void
firmware: stratix10-svc: Convert to platform remove callback returning void
firmware: stratix10-rsu: Convert to platform remove callback returning void
firmware: raspberrypi: Convert to platform remove callback returning void
firmware: qemu_fw_cfg: Convert to platform remove callback returning void
firmware: mtk-adsp-ipc: Convert to platform remove callback returning void
firmware: imx-dsp: Convert to platform remove callback returning void
firmware: coreboot_table: Convert to platform remove callback returning void
firmware: arm_scpi: Convert to platform remove callback returning void
firmware: arm_scmi: Convert to platform remove callback returning void
...
Patch series "workload-specific and memory pressure-driven zswap
writeback", v8.
There are currently several issues with zswap writeback:
1. There is only a single global LRU for zswap, making it impossible to
perform worload-specific shrinking - an memcg under memory pressure
cannot determine which pages in the pool it owns, and often ends up
writing pages from other memcgs. This issue has been previously
observed in practice and mitigated by simply disabling
memcg-initiated shrinking:
https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u
But this solution leaves a lot to be desired, as we still do not
have an avenue for an memcg to free up its own memory locked up in
the zswap pool.
2. We only shrink the zswap pool when the user-defined limit is hit.
This means that if we set the limit too high, cold data that are
unlikely to be used again will reside in the pool, wasting precious
memory. It is hard to predict how much zswap space will be needed
ahead of time, as this depends on the workload (specifically, on
factors such as memory access patterns and compressibility of the
memory pages).
This patch series solves these issues by separating the global zswap LRU
into per-memcg and per-NUMA LRUs, and performs workload-specific (i.e
memcg- and NUMA-aware) zswap writeback under memory pressure. The new
shrinker does not have any parameter that must be tuned by the user, and
can be opted in or out on a per-memcg basis.
As a proof of concept, we ran the following synthetic benchmark: build the
linux kernel in a memory-limited cgroup, and allocate some cold data in
tmpfs to see if the shrinker could write them out and improved the overall
performance. Depending on the amount of cold data generated, we observe
from 14% to 35% reduction in kernel CPU time used in the kernel builds.
This patch (of 6):
The interface of list_lru is based on the assumption that the list node
and the data it represents belong to the same allocated on the correct
node/memcg. While this assumption is valid for existing slab objects LRU
such as dentries and inodes, it is undocumented, and rather inflexible for
certain potential list_lru users (such as the upcoming zswap shrinker and
the THP shrinker). It has caused us a lot of issues during our
development.
This patch changes list_lru interface so that the caller must explicitly
specify numa node and memcg when adding and removing objects. The old
list_lru_add() and list_lru_del() are renamed to list_lru_add_obj() and
list_lru_del_obj(), respectively.
It also extends the list_lru API with a new function, list_lru_putback,
which undoes a previous list_lru_isolate call. Unlike list_lru_add, it
does not increment the LRU node count (as list_lru_isolate does not
decrement the node count). list_lru_putback also allows for explicit
memcg and NUMA node selection.
Link: https://lkml.kernel.org/r/20231130194023.4102148-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-2-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The alloc->mutex is a highly contended lock that causes performance
issues on Android devices. When a low-priority task is given this lock
and it sleeps, it becomes difficult for the task to wake up and complete
its work. This delays other tasks that are also waiting on the mutex.
The problem gets worse when there is memory pressure in the system,
because this increases the contention on the alloc->mutex while the
shrinker reclaims binder pages.
Switching to a spinlock helps to keep the waiters running and avoids the
overhead of waking up tasks. This significantly improves the transaction
latency when the problematic scenario occurs.
The performance impact of this patchset was measured by stress-testing
the binder alloc contention. In this test, several clients of different
priorities send thousands of transactions of different sizes to a single
server. In parallel, pages get reclaimed using the shinker's debugfs.
The test was run on a Pixel 8, Pixel 6 and qemu machine. The results
were similar on all three devices:
after:
| sched | prio | average | max | min |
|--------+------+---------+-----------+---------|
| fifo | 99 | 0.135ms | 1.197ms | 0.022ms |
| fifo | 01 | 0.136ms | 5.232ms | 0.018ms |
| other | -20 | 0.180ms | 7.403ms | 0.019ms |
| other | 19 | 0.241ms | 58.094ms | 0.018ms |
before:
| sched | prio | average | max | min |
|--------+------+---------+-----------+---------|
| fifo | 99 | 0.350ms | 248.730ms | 0.020ms |
| fifo | 01 | 0.357ms | 248.817ms | 0.024ms |
| other | -20 | 0.399ms | 249.906ms | 0.020ms |
| other | 19 | 0.477ms | 297.756ms | 0.022ms |
The key metrics above are the average and max latencies (wall time).
These improvements should roughly translate to p95-p99 latencies on real
workloads. The response time is up to 200x faster in these scenarios and
there is no penalty in the regular path.
Note that it is only possible to convert this lock after a series of
changes made by previous patches. These mainly include refactoring the
sections that might_sleep() and changing the locking order with the
mmap_lock amongst others.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-29-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The locking order currently requires the alloc->mutex to be acquired
first followed by the mmap lock. However, the alloc->mutex is converted
into a spinlock in subsequent commits so the order needs to be reversed
to avoid nesting the sleeping mmap lock under the spinlock.
The shrinker's callback binder_alloc_free_page() is the only place that
needs to be reordered since other functions have been refactored and no
longer nest these locks.
Some minor cosmetic changes are also included in this patch.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-28-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prefer logging vma offsets instead of addresses or simply drop the debug
log altogether if not useful. Note this covers the instances affected by
the switch to store addresses as unsigned long. However, there are other
sections in the driver that could do the same.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-27-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Skip the freelist call immediately as needed, instead of continuing the
pointless checks. Also, drop the debug logs that we don't really need.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-26-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The code in print_binder_buffer() is quite small so it can be collapsed
into its single caller binder_alloc_print_allocated().
No functional change in this patch.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-25-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The code to determine the page range for binder_lru_freelist_del() is
quite obscure. It leverages the buffer_size calculated before doing an
oversized buffer split. This is used to figure out if the last page is
being shared with another active buffer. If so, the page gets trimmed
out of the range as it has been previously removed from the freelist.
This would be equivalent to getting the start page of the next in-use
buffer explicitly. However, the code for this is much larger as we can
see in binder_free_buf_locked() routine. Instead, lets settle on
documenting the tricky step and using better names for now.
I believe an ideal solution would be to count the binder_page->users to
determine when a page should be added or removed from the freelist.
However, this is a much bigger change than what I'm willing to risk at
this time.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-24-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that the page allocation step is done separately we should rename
the binder_free_page_range() and binder_allocate_page_range() functions
to provide a more accurate description of what they do. Lets borrow the
freelist concept used in other parts of the kernel for this.
No functional change here.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-23-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The sections in binder_alloc_new_buf_locked() dealing with oversized
buffers are scattered which makes them difficult to read. Instead,
consolidate this code into a single block to improve readability.
No functional change here.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-22-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The debug information in this statement is already logged earlier in the
same function. We can get rid of this duplicate log.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-21-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split out the insertion of pages to be outside of the alloc->mutex in a
separate binder_install_buffer_pages() routine. Since this is no longer
serialized, we must look at the full range of pages used by the buffers.
The installation is protected with mmap_sem in write mode since multiple
tasks might race to install the same page.
Besides avoiding unnecessary nested locking this helps in preparation of
switching the alloc->mutex into a spinlock_t in subsequent patches.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-20-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Rather than repeatedly initializing some of the binder_lru_page members
during binder_alloc_new_buf(), perform this initialization just once in
binder_alloc_mmap_handler(), after the pages have been created.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-19-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Preallocate new_buffer before acquiring the alloc->mutex and hand it
down to binder_alloc_new_buf_locked(). The new buffer will be used in
the vast majority of requests (measured at 98.2% in field data). The
buffer is discarded otherwise. This change is required in preparation
for transitioning alloc->mutex into a spinlock in subsequent commits.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-18-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of looping through the page range twice to first determine if
the mmap lock is required, simply do it per-page as needed. Split out
all this logic into a separate binder_install_single_page() function.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-17-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move this function up along with binder_alloc_get_page() so that their
prototypes aren't necessary.
No functional change in this patch.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-16-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the low async space calculation to debug_low_async_space_locked().
This logic not only fits better here but also offloads some of the many
tasks currently done in binder_alloc_new_buf_locked().
No functional change in this patch.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-15-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the no-space debugging logic into a separate function. Lets also
mark this branch as unlikely in binder_alloc_new_buf_locked() as most
requests will fit without issue.
Also add a few cosmetic changes and suggestions from checkpatch.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-14-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Binder attributes the buffer allocation to the current->tgid everytime.
There is no need to pass this as a parameter so drop it.
Also add a few touchups to follow the coding guidelines. No functional
changes are introduced in this patch.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-13-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Extract non-critical sections from binder_alloc_new_buf_locked() that
don't require holding the alloc->mutex. While we are here, consolidate
the checks for size overflow and zero-sized padding into a separate
sanitized_size() helper function.
Also add a few touchups to follow the coding guidelines.
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-12-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The binder_update_page_range() function performs both allocation and
freeing of binder pages. However, these two operations are unrelated and
have no common logic. In fact, when a free operation is requested, the
allocation logic is skipped entirely. This behavior makes the error path
unnecessarily complex. To improve readability of the code, this patch
splits the allocation and freeing operations into separate functions.
No functional changes are introduced by this patch.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-11-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The vma addresses in binder are currently stored as void __user *. This
requires casting back and forth between the mm/ api which uses unsigned
long. Since we also do internal arithmetic on these addresses we end up
having to cast them _again_ to an integer type.
Lets stop all the unnecessary casting which kills code readability and
store the virtual addresses as the native unsigned long from mm/. Note
that this approach is preferred over uintptr_t as Linus explains in [1].
Opportunistically add a few cosmetic touchups.
Link: https://lore.kernel.org/all/CAHk-=wj2OHy-5e+srG1fy+ZU00TmZ1NFp6kFLbVLMXHe7A1d-g@mail.gmail.com/ [1]
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-10-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Update the comments of binder_alloc_new_buf() to reflect that the return
value of the function is now ERR_PTR(-errno) on failure.
No functional changes in this patch.
Cc: stable@vger.kernel.org
Fixes: 57ada2fb22 ("binder: add log information for binder transaction failures")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-8-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix minor misspelling of the function in the comment section.
No functional changes in this patch.
Cc: stable@vger.kernel.org
Fixes: 0f966cba95 ("binder: add flag to clear buffer on txn complete")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-7-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Each transaction is associated with a 'struct binder_buffer' that stores
the metadata about its buffer area. Since commit 74310e06be ("android:
binder: Move buffer out of area shared with user space") this struct is
no longer embedded within the buffer itself but is instead allocated on
the heap to prevent userspace access to this driver-exclusive info.
Unfortunately, the space of this struct is still being accounted for in
the total buffer size calculation, specifically for async transactions.
This results in an additional 104 bytes added to every async buffer
request, and this area is never used.
This wasted space can be substantial. If we consider the maximum mmap
buffer space of SZ_4M, the driver will reserve half of it for async
transactions, or 0x200000. This area should, in theory, accommodate up
to 262,144 buffers of the minimum 8-byte size. However, after adding
the extra 'sizeof(struct binder_buffer)', the total number of buffers
drops to only 18,724, which is a sad 7.14% of the actual capacity.
This patch fixes the buffer size calculation to enable the utilization
of the entire async buffer space. This is expected to reduce the number
of -ENOSPC errors that are seen on the field.
Fixes: 74310e06be ("android: binder: Move buffer out of area shared with user space")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-6-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the padding of 0-sized buffers to an earlier stage to account for
this round up during the alloc->free_async_space check.
Fixes: 74310e06be ("android: binder: Move buffer out of area shared with user space")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-5-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Task A calls binder_update_page_range() to allocate and insert pages on
a remote address space from Task B. For this, Task A pins the remote mm
via mmget_not_zero() first. This can race with Task B do_exit() and the
final mmput() refcount decrement will come from Task A.
Task A | Task B
------------------+------------------
mmget_not_zero() |
| do_exit()
| exit_mm()
| mmput()
mmput() |
exit_mmap() |
remove_vma() |
fput() |
In this case, the work of ____fput() from Task B is queued up in Task A
as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup
work gets executed. However, Task A instead sleep, waiting for a reply
from Task B that never comes (it's dead).
This means the binder_deferred_release() is blocked until an unrelated
binder event forces Task A to go back to userspace. All the associated
death notifications will also be delayed until then.
In order to fix this use mmput_async() that will schedule the work in
the corresponding mm->async_put_work WQ instead of Task A.
Fixes: 457b9a6f09 ("Staging: android: add binder driver")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-4-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The mmap read lock is used during the shrinker's callback, which means
that using alloc->vma pointer isn't safe as it can race with munmap().
As of commit dd2283f260 ("mm: mmap: zap pages with read mmap_sem in
munmap") the mmap lock is downgraded after the vma has been isolated.
I was able to reproduce this issue by manually adding some delays and
triggering page reclaiming through the shrinker's debug sysfs. The
following KASAN report confirms the UAF:
==================================================================
BUG: KASAN: slab-use-after-free in zap_page_range_single+0x470/0x4b8
Read of size 8 at addr ffff356ed50e50f0 by task bash/478
CPU: 1 PID: 478 Comm: bash Not tainted 6.6.0-rc5-00055-g1c8b86a3799f-dirty #70
Hardware name: linux,dummy-virt (DT)
Call trace:
zap_page_range_single+0x470/0x4b8
binder_alloc_free_page+0x608/0xadc
__list_lru_walk_one+0x130/0x3b0
list_lru_walk_node+0xc4/0x22c
binder_shrink_scan+0x108/0x1dc
shrinker_debugfs_scan_write+0x2b4/0x500
full_proxy_write+0xd4/0x140
vfs_write+0x1ac/0x758
ksys_write+0xf0/0x1dc
__arm64_sys_write+0x6c/0x9c
Allocated by task 492:
kmem_cache_alloc+0x130/0x368
vm_area_alloc+0x2c/0x190
mmap_region+0x258/0x18bc
do_mmap+0x694/0xa60
vm_mmap_pgoff+0x170/0x29c
ksys_mmap_pgoff+0x290/0x3a0
__arm64_sys_mmap+0xcc/0x144
Freed by task 491:
kmem_cache_free+0x17c/0x3c8
vm_area_free_rcu_cb+0x74/0x98
rcu_core+0xa38/0x26d4
rcu_core_si+0x10/0x1c
__do_softirq+0x2fc/0xd24
Last potentially related work creation:
__call_rcu_common.constprop.0+0x6c/0xba0
call_rcu+0x10/0x1c
vm_area_free+0x18/0x24
remove_vma+0xe4/0x118
do_vmi_align_munmap.isra.0+0x718/0xb5c
do_vmi_munmap+0xdc/0x1fc
__vm_munmap+0x10c/0x278
__arm64_sys_munmap+0x58/0x7c
Fix this issue by performing instead a vma_lookup() which will fail to
find the vma that was isolated before the mmap lock downgrade. Note that
this option has better performance than upgrading to a mmap write lock
which would increase contention. Plus, mmap_write_trylock() has been
recently removed anyway.
Fixes: dd2283f260 ("mm: mmap: zap pages with read mmap_sem in munmap")
Cc: stable@vger.kernel.org
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-3-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In binder_init(), the destruction of binder_alloc_shrinker_init() is not
performed in the wrong path, which will cause memory leaks. So this commit
introduces binder_alloc_shrinker_exit() and calls it in the wrong path to
fix that.
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Fixes: f2517eb76f ("android: binder: Add global lru shrinker to binder")
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20230625154937.64316-1-qi.zheng@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ cmllamas: clean forward port from commit 015ac18be7de ("binder: fix
UAF of alloc->vma in race with munmap()") in 5.10 stable. It is needed
in mainline after the revert of commit a43cfc87ca ("android: binder:
stop saving a pointer to the VMA") as pointed out by Liam. The commit
log and tags have been tweaked to reflect this. ]
In commit 720c241924 ("ANDROID: binder: change down_write to
down_read") binder assumed the mmap read lock is sufficient to protect
alloc->vma inside binder_update_page_range(). This used to be accurate
until commit dd2283f260 ("mm: mmap: zap pages with read mmap_sem in
munmap"), which now downgrades the mmap_lock after detaching the vma
from the rbtree in munmap(). Then it proceeds to teardown and free the
vma with only the read lock held.
This means that accesses to alloc->vma in binder_update_page_range() now
will race with vm_area_free() in munmap() and can cause a UAF as shown
in the following KASAN trace:
==================================================================
BUG: KASAN: use-after-free in vm_insert_page+0x7c/0x1f0
Read of size 8 at addr ffff16204ad00600 by task server/558
CPU: 3 PID: 558 Comm: server Not tainted 5.10.150-00001-gdc8dcf942daa #1
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x2a0
show_stack+0x18/0x2c
dump_stack+0xf8/0x164
print_address_description.constprop.0+0x9c/0x538
kasan_report+0x120/0x200
__asan_load8+0xa0/0xc4
vm_insert_page+0x7c/0x1f0
binder_update_page_range+0x278/0x50c
binder_alloc_new_buf+0x3f0/0xba0
binder_transaction+0x64c/0x3040
binder_thread_write+0x924/0x2020
binder_ioctl+0x1610/0x2e5c
__arm64_sys_ioctl+0xd4/0x120
el0_svc_common.constprop.0+0xac/0x270
do_el0_svc+0x38/0xa0
el0_svc+0x1c/0x2c
el0_sync_handler+0xe8/0x114
el0_sync+0x180/0x1c0
Allocated by task 559:
kasan_save_stack+0x38/0x6c
__kasan_kmalloc.constprop.0+0xe4/0xf0
kasan_slab_alloc+0x18/0x2c
kmem_cache_alloc+0x1b0/0x2d0
vm_area_alloc+0x28/0x94
mmap_region+0x378/0x920
do_mmap+0x3f0/0x600
vm_mmap_pgoff+0x150/0x17c
ksys_mmap_pgoff+0x284/0x2dc
__arm64_sys_mmap+0x84/0xa4
el0_svc_common.constprop.0+0xac/0x270
do_el0_svc+0x38/0xa0
el0_svc+0x1c/0x2c
el0_sync_handler+0xe8/0x114
el0_sync+0x180/0x1c0
Freed by task 560:
kasan_save_stack+0x38/0x6c
kasan_set_track+0x28/0x40
kasan_set_free_info+0x24/0x4c
__kasan_slab_free+0x100/0x164
kasan_slab_free+0x14/0x20
kmem_cache_free+0xc4/0x34c
vm_area_free+0x1c/0x2c
remove_vma+0x7c/0x94
__do_munmap+0x358/0x710
__vm_munmap+0xbc/0x130
__arm64_sys_munmap+0x4c/0x64
el0_svc_common.constprop.0+0xac/0x270
do_el0_svc+0x38/0xa0
el0_svc+0x1c/0x2c
el0_sync_handler+0xe8/0x114
el0_sync+0x180/0x1c0
[...]
==================================================================
To prevent the race above, revert back to taking the mmap write lock
inside binder_update_page_range(). One might expect an increase of mmap
lock contention. However, binder already serializes these calls via top
level alloc->mutex. Also, there was no performance impact shown when
running the binder benchmark tests.
Fixes: c0fd210178 ("Revert "android: binder: stop saving a pointer to the VMA"")
Fixes: dd2283f260 ("mm: mmap: zap pages with read mmap_sem in munmap")
Reported-by: Jann Horn <jannh@google.com>
Closes: https://lore.kernel.org/all/20230518144052.xkj6vmddccq4v66b@revolver
Cc: <stable@vger.kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20230519195950.1775656-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bring back the original lockless design in binder_alloc to determine
whether the buffer setup has been completed by the ->mmap() handler.
However, this time use smp_load_acquire() and smp_store_release() to
wrap all the ordering in a single macro call.
Also, add comments to make it evident that binder uses alloc->vma to
determine when the binder_alloc has been fully initialized. In these
scenarios acquiring the mmap_lock is not required.
Fixes: a43cfc87ca ("android: binder: stop saving a pointer to the VMA")
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20230502201220.1756319-3-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit a43cfc87ca.
This patch fixed an issue reported by syzkaller in [1]. However, this
turned out to be only a band-aid in binder. The root cause, as bisected
by syzkaller, was fixed by commit 5789151e48 ("mm/mmap: undo ->mmap()
when mas_preallocate() fails"). We no longer need the patch for binder.
Reverting such patch allows us to have a lockless access to alloc->vma
in specific cases where the mmap_lock is not required. This approach
avoids the contention that caused a performance regression.
[1] https://lore.kernel.org/all/0000000000004a0dbe05e1d749e0@google.com
[cmllamas: resolved conflicts with rework of alloc->mm and removal of
binder_alloc_set_vma() also fixed comment section]
Fixes: a43cfc87ca ("android: binder: stop saving a pointer to the VMA")
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20230502201220.1756319-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 44e602b4e5.
This caused a performance regression particularly when pages are getting
reclaimed. We don't need to acquire the mmap_lock to determine when the
binder buffer has been fully initialized. A subsequent patch will bring
back the lockless approach for this.
[cmllamas: resolved trivial conflicts with renaming of alloc->mm]
Fixes: 44e602b4e5 ("binder_alloc: add missing mmap_lock calls when using the VMA")
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20230502201220.1756319-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zap_page_range was originally designed to unmap pages within an address
range that could span multiple vmas. While working on [1], it was
discovered that all callers of zap_page_range pass a range entirely within
a single vma. In addition, the mmu notification call within zap_page
range does not correctly handle ranges that span multiple vmas. When
crossing a vma boundary, a new mmu_notifier_range_init/end call pair with
the new vma should be made.
Instead of fixing zap_page_range, do the following:
- Create a new routine zap_vma_pages() that will remove all pages within
the passed vma. Most users of zap_page_range pass the entire vma and
can use this new routine.
- For callers of zap_page_range not passing the entire vma, instead call
zap_page_range_single().
- Remove zap_page_range.
[1] https://lore.kernel.org/linux-mm/20221114235507.294320-2-mike.kravetz@oracle.com/
Link: https://lkml.kernel.org/r/20230104002732.232573-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com> [s390]
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since commit 1da52815d5 ("binder: fix alloc->vma_vm_mm null-ptr
dereference") binder caches a pointer to the current->mm during open().
This fixes a null-ptr dereference reported by syzkaller. Unfortunately,
it also opens the door for a process to update its mm after the open(),
(e.g. via execve) making the cached alloc->mm pointer invalid.
Things get worse when the process continues to mmap() a vma. From this
point forward, binder will attempt to find this vma using an obsolete
alloc->mm reference. Such as in binder_update_page_range(), where the
wrong vma is obtained via vma_lookup(), yet binder proceeds to happily
insert new pages into it.
To avoid this issue fail the ->mmap() callback if we detect a mismatch
between the vma->vm_mm and the original alloc->mm pointer. This prevents
alloc->vm_addr from getting set, so that any subsequent vma_lookup()
calls fail as expected.
Fixes: 1da52815d5 ("binder: fix alloc->vma_vm_mm null-ptr dereference")
Reported-by: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org> # 5.15+
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20221104231235.348958-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
