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As requested by Ricardo and Jakub, implement report and context modes for
the secs_to_jiffies Coccinelle script. While here, add the option to look
for opportunities to use secs_to_jiffies() in headers.
Link: https://lkml.kernel.org/r/20250703225145.152288-1-eahariha@linux.microsoft.com
Signed-off-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Closes: https://lore.kernel.org/all/20250129-secs_to_jiffles-v1-1-35a5e16b9f03@chromium.org/
Closes: https://lore.kernel.org/all/20250221162107.409ae333@kernel.org/
Tested-by: Ricardo Ribalda <ribalda@chromium.org>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add a dedicated core parameter 'panic_console_replay' for controlling
console replay, and add note that 'panic_print' sysctl interface will be
obsoleted by 'panic_sys_info' and 'panic_console_replay'. When it
happens, the SYS_INFO_PANIC_CONSOLE_REPLAY can be removed as well.
Link: https://lkml.kernel.org/r/20250703021004.42328-6-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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'panic_sys_info=' sysctl interface is already added for runtime setting.
Add counterpart kernel cmdline option for boottime setting.
Link: https://lkml.kernel.org/r/20250703021004.42328-5-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Bitmap definition for 'panic_print' is hard to remember and decode. Add
'panic_sys_info='sysctl to take human readable string like
"tasks,mem,timers,locks,ftrace,..." and translate it into bitmap.
The detailed mapping is:
SYS_INFO_TASKS "tasks"
SYS_INFO_MEM "mem"
SYS_INFO_TIMERS "timers"
SYS_INFO_LOCKS "locks"
SYS_INFO_FTRACE "ftrace"
SYS_INFO_ALL_CPU_BT "all_bt"
SYS_INFO_BLOCKED_TASKS "blocked_tasks"
[nathan@kernel.org: add __maybe_unused to sys_info_avail]
Link: https://lkml.kernel.org/r/20250708-fix-clang-sys_info_avail-warning-v1-1-60d239eacd64@kernel.org
Link: https://lkml.kernel.org/r/20250703021004.42328-4-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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'panic_print' was introduced to help debugging kernel panic by dumping
different kinds of system information like tasks' call stack, memory,
ftrace buffer, etc. Actually this function could also be used to help
debugging other cases like task-hung, soft/hard lockup, etc. where user
may need the snapshot of system info at that time.
Extract system info dump function related code from panic.c to separate
file sys_info.[ch], for wider usage by other kernel parts for debugging.
Also modify the macro names about singulars/plurals.
Link: https://lkml.kernel.org/r/20250703021004.42328-3-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "generalize panic_print's dump function to be used by other
kernel parts", v3.
When working on kernel stability issues, panic, task-hung and
software/hardware lockup are frequently met. And to debug them, user may
need lots of system information at that time, like task call stacks, lock
info, memory info etc.
panic case already has panic_print_sys_info() for this purpose, and has a
'panic_print' bitmask to control what kinds of information is needed,
which is also helpful to debug other task-hung and lockup cases.
So this patchset extracts the function out to a new file 'lib/sys_info.c',
and makes it available for other cases which also need to dump system info
for debugging.
Also as suggested by Petr Mladek, add 'panic_sys_info=' interface to take
human readable string like "tasks,mem,locks,timers,ftrace,....", and
eventually obsolete the current 'panic_print' bitmap interface.
In RFC and V1 version, hung_task and SW/HW watchdog modules are enabled
with the new sys_info dump interface. In v2, they are kept out for better
review of current change, and will be posted later.
Locally these have been used in our bug chasing for stability issues and
was proven helpful.
Many thanks to Petr Mladek for great suggestions on both the code and
architectures!
This patch (of 5):
Currently the panic_print_sys_info() was called twice with different
parameters to handle console replay case, which is kind of confusing.
Add panic_console_replay() explicitly and rename
'PANIC_PRINT_ALL_PRINTK_MSG' to 'PANIC_CONSOLE_REPLAY', to make the code
straightforward. The related kernel document is also updated.
Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20250703021004.42328-2-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Implement the crashkernel CMA reservation for x86:
- enable parsing of the cma suffix by parse_crashkernel()
- reserve memory with reserve_crashkernel_cma()
- add the CMA-reserved ranges to the e820 map for the crash kernel
- exclude the CMA-reserved ranges from vmcore
Link: https://lkml.kernel.org/r/aEqp1LD2og4QeBw9@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When re-using the CMA area for kdump there is a risk of pending DMA into
pinned user pages in the CMA area.
Pages residing in CMA areas can usually not get long-term pinned and are
instead migrated away from the CMA area, so long-term pinning is typically
not a concern. (BUGs in the kernel might still lead to long-term pinning
of such pages if everything goes wrong.)
Pages pinned without FOLL_LONGTERM remain in the CMA and may possibly be
the source or destination of a pending DMA transfer.
Although there is no clear specification how long a page may be pinned
without FOLL_LONGTERM, pinning without the flag shows an intent of the
caller to only use the memory for short-lived DMA transfers, not a
transfer initiated by a device asynchronously at a random time in the
future.
Add a delay of CMA_DMA_TIMEOUT_SEC seconds before starting the kdump
kernel, giving such short-lived DMA transfers time to finish before the
CMA memory is re-used by the kdump kernel.
Set CMA_DMA_TIMEOUT_SEC to 10 seconds - chosen arbitrarily as both a huge
margin for a DMA transfer, yet not increasing the kdump time too
significantly.
Link: https://lkml.kernel.org/r/aEqpgDIBndZ5LXSo@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Describe the new crashkernel ",cma" suffix in Documentation/
Link: https://lkml.kernel.org/r/aEqpQwUy6gqSiUkV@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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reserve_crashkernel_cma() reserves CMA ranges for the crash kernel. If
allocating the requested size fails, try to reserve in smaller blocks.
Store the reserved ranges in the crashk_cma_ranges array and the number of
ranges in crashk_cma_cnt.
Link: https://lkml.kernel.org/r/aEqpBwOy_ekm0gw9@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "kdump: crashkernel reservation from CMA", v5.
This series implements a way to reserve additional crash kernel memory
using CMA.
Currently, all the memory for the crash kernel is not usable by the 1st
(production) kernel. It is also unmapped so that it can't be corrupted by
the fault that will eventually trigger the crash. This makes sense for
the memory actually used by the kexec-loaded crash kernel image and initrd
and the data prepared during the load (vmcoreinfo, ...). However, the
reserved space needs to be much larger than that to provide enough
run-time memory for the crash kernel and the kdump userspace. Estimating
the amount of memory to reserve is difficult. Being too careful makes
kdump likely to end in OOM, being too generous takes even more memory from
the production system. Also, the reservation only allows reserving a
single contiguous block (or two with the "low" suffix). I've seen systems
where this fails because the physical memory is fragmented.
By reserving additional crashkernel memory from CMA, the main crashkernel
reservation can be just large enough to fit the kernel and initrd image,
minimizing the memory taken away from the production system. Most of the
run-time memory for the crash kernel will be memory previously available
to userspace in the production system. As this memory is no longer
wasted, the reservation can be done with a generous margin, making kdump
more reliable. Kernel memory that we need to preserve for dumping is
normally not allocated from CMA, unless it is explicitly allocated as
movable. Currently this is only the case for memory ballooning and zswap.
Such movable memory will be missing from the vmcore. User data is
typically not dumped by makedumpfile. When dumping of user data is
intended this new CMA reservation cannot be used.
There are five patches in this series:
The first adds a new ",cma" suffix to the recenly introduced generic
crashkernel parsing code. parse_crashkernel() takes one more argument to
store the cma reservation size.
The second patch implements reserve_crashkernel_cma() which performs the
reservation. If the requested size is not available in a single range,
multiple smaller ranges will be reserved.
The third patch updates Documentation/, explicitly mentioning the
potential DMA corruption of the CMA-reserved memory.
The fourth patch adds a short delay before booting the kdump kernel,
allowing pending DMA transfers to finish.
The fifth patch enables the functionality for x86 as a proof of
concept. There are just three things every arch needs to do:
- call reserve_crashkernel_cma()
- include the CMA-reserved ranges in the physical memory map
- exclude the CMA-reserved ranges from the memory available
through /proc/vmcore by excluding them from the vmcoreinfo
PT_LOAD ranges.
Adding other architectures is easy and I can do that as soon as this
series is merged.
With this series applied, specifying
crashkernel=100M craskhernel=1G,cma
on the command line will make a standard crashkernel reservation
of 100M, where kexec will load the kernel and initrd.
An additional 1G will be reserved from CMA, still usable by the production
system. The crash kernel will have 1.1G memory available. The 100M can
be reliably predicted based on the size of the kernel and initrd.
The new cma suffix is completely optional. When no
crashkernel=size,cma is specified, everything works as before.
This patch (of 5):
Add a new cma_size parameter to parse_crashkernel(). When not NULL, call
__parse_crashkernel to parse the CMA reservation size from
"crashkernel=size,cma" and store it in cma_size.
Set cma_size to NULL in all calls to parse_crashkernel().
Link: https://lkml.kernel.org/r/aEqnxxfLZMllMC8I@dwarf.suse.cz
Link: https://lkml.kernel.org/r/aEqoQckgoTQNULnh@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Both callers of set_page_owner_migrate_reason() use folios. Convert the
function to take a folio directly and move the &folio->page conversion
inside __set_page_owner_migrate_reason().
Link: https://lkml.kernel.org/r/20250711145910.90135-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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strcpy() is deprecated; use memcpy() instead.
Not copying the NUL terminator is safe because strncpy_from_user() would
overwrite it anyway by appending uname to the destination buffer at index
MFD_NAME_PREFIX_LEN.
No functional changes intended.
Link: https://github.com/KSPP/linux/issues/88
Link: https://lkml.kernel.org/r/20250712174516.64243-2-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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All damon_callback usages are replicated by damon_call() and damos_walk().
Time to say goodbye. Remove damon_callback.
Link: https://lkml.kernel.org/r/20250712195016.151108-15-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON core layer does target cleanup on its own. Remove duplicated and
unnecessarily selective cleanup attempts in DAMON sysfs interface.
Link: https://lkml.kernel.org/r/20250712195016.151108-14-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When kdamond_fn() completes, the targets are kept. Those are kept to let
callers do additional cleanups if they need. There are no such additional
cleanups though. DAMON sysfs interface deallocates those in
before_terminate() callback, to reduce unnecessary memory usage, for
[f]vaddr use case. Just destroy the targets for every case in the core
layer. This saves more memory and simplifies the logic.
Link: https://lkml.kernel.org/r/20250712195016.151108-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The function was introduced for putting pids and deallocating unnecessary
targets. Hence it is called before damon_destroy_ctx(). Now vaddr puts
pid for each target destruction (cleanup_target()). damon_destroy_ctx()
deallocates the targets anyway. So damon_sysfs_destroy_targets() has no
reason to exist. Remove it.
Link: https://lkml.kernel.org/r/20250712195016.151108-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Implement cleanup_target() callback for [f]vaddr, which calls put_pid()
for each target that will be destroyed. Also remove redundant put_pid()
calls in core, sysfs and sample modules, which were required to be done
redundantly due to the lack of such self cleanup in vaddr.
Link: https://lkml.kernel.org/r/20250712195016.151108-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Some DAMON operation sets may need additional cleanup per target. For
example, [f]vaddr need to put pids of each target. Each user and core
logic is doing that redundantly. Add another DAMON ops callback that will
be used for doing such cleanups in operations set layer.
[sj@kernel.org: add kernel-doc comment for damon_operations->cleanup_target]
Link: https://lkml.kernel.org/r/20250715185239.89152-2-sj@kernel.org
[sj@kernel.org: remove damon_ctx->callback kernel-doc comment]
Link: https://lkml.kernel.org/r/20250715185239.89152-3-sj@kernel.org
Link: https://lkml.kernel.org/r/20250712195016.151108-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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damon_operations.cleanup() is documented to be called for kdamond
termination, but also being called for targets destruction, which is done
for any damon_ctx destruction. Nobody is using the callback for now,
though. Remove the cleanup() call under the destruction.
Link: https://lkml.kernel.org/r/20250712195016.151108-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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wsse uses damon_callback for periodically reading DAMON internal data.
Use its alternative, damon_call() repeat mode.
Link: https://lkml.kernel.org/r/20250712195016.151108-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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prcl uses damon_callback for periodically reading DAMON internal data.
Use its alternative, damon_call() repeat mode.
Link: https://lkml.kernel.org/r/20250712195016.151108-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON_LRU_SORT uses damon_callback for periodically reading and writing
DAMON internal data and parameters. Use its alternative, damon_call()
repeat mode.
Link: https://lkml.kernel.org/r/20250712195016.151108-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON_RECLAIM uses damon_callback for periodically reading and writing
DAMON internal data and parameters. Use its alternative, damon_call()
repeat mode.
Link: https://lkml.kernel.org/r/20250712195016.151108-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON_STAT uses damon_callback for periodically reading DAMON internal
data. Use its alternative, damon_call() repeat mode.
Link: https://lkml.kernel.org/r/20250712195016.151108-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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damon_call() can be useful for reading or writing DAMON internal data for
one time. A common pattern of DAMON core usage from DAMON modules is
doing such reads and writes repeatedly, for example, to periodically
update the DAMOS stats. To do that with damon_call(), callers should call
damon_call() repeatedly, with their own delay loop. Each caller doing
that is repetitive. Introduce a repeat mode damon_call(). Callers can
use the mode by setting a new field in damon_call_control. If the mode is
turned on, damon_call() returns success immediately, and DAMON repeats
invoking the callback function inside the kdamond main loop.
Link: https://lkml.kernel.org/r/20250712195016.151108-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/damon: remove damon_callback".
damon_callback was the only way for communicating with DAMON for contexts
running on its worker thread. The interface is flexible and simple. But
as DAMON evolves with more features, damon_callback has become somewhat
too old. With runtime parameters update, for example, its lack of
synchronization support was found to be inconvenient. Arguably it is also
not easy to use correctly since the callers should understand when each
callback is called, and implication of the return values from the
callbacks.
To replace it, damon_call() and damos_walk() are introduced. And those
replaced a few damon_callback use cases. Some use cases of damon_callback
such as parallel or repetitive DAMON internal data reading and additional
cleanups cannot simply be replaced by damon_call() and damos_walk(),
though.
To allow those replaceable, extend damon_call() for parallel and/or
repeated callbacks and modify the core/ops layers for additional resources
cleanup. With the updates, replace the remaining damon_callback usages
and finally say goodbye to damon_callback.
This patch (of 14):
Calling damon_call() while it is serving for another parallel thread
immediately fails with -EBUSY. The caller should call it again, later.
Each caller implementing such retry logic would be redundant. Accept
parallel damon_call() requests and do the wait instead of the caller.
Link: https://lkml.kernel.org/r/20250712195016.151108-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250712195016.151108-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Set min_brk to mm->start_brk by default, and override it with mm->end_data
only when CONFIG_COMPAT_BRK is enabled and brk_randomized is false.
This makes the logic clearer with no functional change.
Link: https://lkml.kernel.org/r/20250710025859.926355-1-liuqiye2025@163.com
Signed-off-by: Xuanye Liu <liuqiye2025@163.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
folio_nr_pages() is faster helper function to get the number of pages when
NR_PAGES_IN_LARGE_FOLIO is enabled.
Link: https://lkml.kernel.org/r/20250710060451.3535957-1-chizhiling@163.com
Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When pmd_to_hmm_pfn_flags() is unused, it prevents kernel builds with
clang, `make W=1` and CONFIG_TRANSPARENT_HUGEPAGE=n:
mm/hmm.c:186:29: warning: unused function 'pmd_to_hmm_pfn_flags' [-Wunused-function]
Fix this by moving the function to the respective existing ifdeffery
for its the only user.
See also:
6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 build")
Link: https://lkml.kernel.org/r/20250710082403.664093-1-andriy.shevchenko@linux.intel.com
Fixes: 992de9a8b751 ("mm/hmm: allow to mirror vma of a file on a DAX backed filesystem")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This adds support for allowing proactive reclaim in general on a NUMA
system. A per-node interface extends support for beyond a memcg-specific
interface, respecting the current semantics of memory.reclaim: respecting
aging LRU and not supporting artificially triggering eviction on nodes
belonging to non-bottom tiers.
This patch allows userspace to do:
echo "512M swappiness=10" > /sys/devices/system/node/nodeX/reclaim
One of the premises for this is to semantically align as best as possible
with memory.reclaim. During a brief time memcg did support nodemask until
55ab834a86a9 (Revert "mm: add nodes= arg to memory.reclaim"), for which
semantics around reclaim (eviction) vs demotion were not clear, rendering
charging expectations to be broken.
With this approach:
1. Users who do not use memcg can benefit from proactive reclaim. The
memcg interface is not NUMA aware and there are usecases that are
focusing on NUMA balancing rather than workload memory footprint.
2. Proactive reclaim on top tiers will trigger demotion, for which
memory is still byte-addressable. Reclaiming on the bottom nodes will
trigger evicting to swap (the traditional sense of reclaim). This
follows the semantics of what is today part of the aging process on
tiered memory, mirroring what every other form of reclaim does
(reactive and memcg proactive reclaim). Furthermore per-node proactive
reclaim is not as susceptible to the memcg charging problem mentioned
above.
3. Unlike the nodes= arg, this interface avoids confusing semantics,
such as what exactly the user wants when mixing top-tier and low-tier
nodes in the nodemask. Further per-node interface is less exposed to
"free up memory in my container" usecases, where eviction is intended.
4. Users that *really* want to free up memory can use proactive
reclaim on nodes knowingly to be on the bottom tiers to force eviction
in a natural way - higher access latencies are still better than swap.
If compelled, while no guarantees and perhaps not worth the effort,
users could also also potentially follow a ladder-like approach to
eventually free up the memory. Alternatively, perhaps an 'evict'
option could be added to the parameters for both memory.reclaim and
per-node interfaces to force this action unconditionally.
[akpm@linux-foundation.org: user_proactive_reclaim(): return -EBUSY on PGDAT_RECLAIM_LOCKED contention, per Roman]
[dave@stgolabs.net: memcg && node is also a bogus case, per Shakeel]
Link: https://lkml.kernel.org/r/20250717235604.2atyx2aobwowpge3@offworld
Link: https://lkml.kernel.org/r/20250623185851.830632-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
As this will be called from non page allocator paths for proactive
reclaim, allow users to pass the sc and nr of pages, and adjust the return
value as well. No change in semantics.
Link: https://lkml.kernel.org/r/20250623185851.830632-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This adds a general call for both parsing as well as the common reclaim
semantics. memcg is still the only user and no change in semantics.
[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
Link: https://lkml.kernel.org/r/20250623185851.830632-3-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: per-node proactive reclaim", v2.
This adds support for allowing proactive reclaim in general on a NUMA
system. A per-node interface extends support for beyond a memcg-specific
interface, respecting the current semantics of memory.reclaim: respecting
aging LRU and not supporting artificially triggering eviction on nodes
belonging to non-bottom tiers.
This patch allows userspace to do:
echo 512M swappiness=10 > /sys/devices/system/node/nodeX/reclaim
One of the premises for this is to semantically align as best as possible
with memory.reclaim. During a brief time memcg did support nodemask until
55ab834a86a9 (Revert "mm: add nodes= arg to memory.reclaim"), for which
semantics around reclaim (eviction) vs demotion were not clear, rendering
charging expectations to be broken.
With this approach:
1. Users who do not use memcg can benefit from proactive reclaim.
2. Proactive reclaim on top tiers will trigger demotion, for which
memory is still byte-addressable. Reclaiming on the bottom nodes will
trigger evicting to swap (the traditional sense of reclaim). This
follows the semantics of what is today part of the aging process on
tiered memory, mirroring what every other form of reclaim does
(reactive and memcg proactive reclaim). Furthermore per-node proactive
reclaim is not as susceptible to the memcg charging problem mentioned
above.
3. Unlike memcg, there should be no surprises of callers expecting
reclaim but instead got a demotion. Essentially relying on behavior of
shrink_folio_list() after 6b426d071419 ("mm: disable top-tier fallback
to reclaim on proactive reclaim"), without the expectations of
try_to_free_mem_cgroup_pages().
4. Unlike the nodes= arg, this interface avoids confusing semantics,
such as what exactly the user wants when mixing top-tier and low-tier
nodes in the nodemask. Further per-node interface is less exposed to
"free up memory in my container" usecases, where eviction is intended.
5. Users that *really* want to free up memory can use proactive
reclaim on nodes knowingly to be on the bottom tiers to force eviction
in a natural way - higher access latencies are still better than swap.
If compelled, while no guarantees and perhaps not worth the effort,
users could also also potentially follow a ladder-like approach to
eventually free up the memory. Alternatively, perhaps an 'evict'
option could be added to the parameters for both memory.reclaim and
per-node interfaces to force this action unconditionally.
This patch (of 4):
... rather benign but keep proper ending order.
Link: https://lkml.kernel.org/r/20250623185851.830632-1-dave@stgolabs.net
Link: https://lkml.kernel.org/r/20250623185851.830632-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There are no callers of unmap_and_put_page() left. Remove it.
Link: https://lkml.kernel.org/r/20250709194017.927978-6-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jordan Rome <linux@jordanrome.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Use kmap_local_folio() instead of kmap_local_page(). Replaces 2 calls to
compound_head() with one.
This prepares us for the removal of unmap_and_put_page().
Link: https://lkml.kernel.org/r/20250709194017.927978-5-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jordan Rome <linux@jordanrome.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Remove unmap_and_put_page()".
This patchset uses folios in both the callers of unmap_and_put_page(),
saving a couple calls to compound_head() wrappers.
This patch (of 3):
Use kmap_local_folio() instead of kmap_local_page(). Replaces 2 calls to
compound_head() from unmap_and_put_page() with one.
This prepares us for the removal of unmap_and_put_page().
Link: https://lkml.kernel.org/r/20250709194017.927978-3-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20250709194017.927978-4-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jordan Rome <linux@jordanrome.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The paddr versions of migrate_{hot/cold} filter out folios from migration
based on the scheme's filters. This patch does the same for the vaddr
versions of those schemes.
The filtering code is mostly the same for the paddr and vaddr versions.
The exception is the young filter. paddr determines if a page is young by
doing a folio rmap walk to find the page table entries corresponding to
the folio. However, vaddr schemes have easier access to the page tables,
so we add some logic to avoid the extra work.
Link: https://lkml.kernel.org/r/20250709005952.17776-14-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This patch moves damos_pa_filter_match and the functions it calls to
ops-common, renaming it to damos_folio_filter_match. Doing so allows us
to share the filtering logic for the vaddr version of the
migrate_{hot,cold} schemes.
Link: https://lkml.kernel.org/r/20250709005952.17776-13-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damos->migrate_dests provides a list of nodes the migrate_{hot,cold}
actions should migrate to, as well as the weights which specify the ratio
pages should be migrated to each destination node.
This patch interleaves pages in the migrate_{hot,cold} actions according
to the information provided in damos->migrate_dests if it is used. The
interleaving algorithm used is similar to the one used in
weighted_interleave_nid(). If damos->migration_dests is not provided, the
actions migrate pages to the node specified in damos->target_nid as
before.
Link: https://lkml.kernel.org/r/20250709005952.17776-12-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Document that the migrate_{hot,cold} schemes can be used by the vaddr
operations set.
Link: https://lkml.kernel.org/r/20250709005952.17776-11-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
migrate_{hot,cold} are paddr schemes that are used to migrate hot/cold
data to a specified node. However, these schemes are only available when
doing physical address monitoring. This patch adds an implementation for
them virtual address monitoring as well.
Link: https://lkml.kernel.org/r/20250709005952.17776-10-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This patch moves the damon_pa_migrate_pages function along with its
corresponding helper functions from paddr to ops-common. The function
prefix of "damon_pa_" was also changed to just "damon_" accordingly.
This patch will allow page migration to be available to vaddr schemes as
well as paddr schemes.
Link: https://lkml.kernel.org/r/20250709005952.17776-9-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When committing new scheme parameters from the sysfs, copy the
migrate_dests struct of the source schemes into the destination schemes.
Link: https://lkml.kernel.org/r/20250709005952.17776-8-bijan311@gmail.com
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Document the newly added DAMOS action destination directory of the DAMON
sysfs interface on the usage document.
Link: https://lkml.kernel.org/r/20250709005952.17776-7-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Bijan Tabatabai <bijantabatab@micron.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Document the new DAMOS action destinations sysfs directories on ABI doc.
Link: https://lkml.kernel.org/r/20250709005952.17776-6-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Bijan Tabatabai <bijantabatab@micron.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Pass user-specified multiple DAMOS action destinations and their weights
to DAMON core API, so that user requests can really work.
Link: https://lkml.kernel.org/r/20250709005952.17776-5-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
DAMOS_MIGRATE_{HOT,COLD} can have multiple action destinations and their
weights. Implement sysfs directory named 'dests' under each scheme
directory to let DAMON sysfs ABI users utilize the feature. The interface
is similar to other multiple parameters directory like kdamonds or
filters. The directory contains only nr_dests file initially. Writing a
number of desired destinations to nr_dests creates directories of the
number. Each of the created directories has two files named id and
weight. Users can then write the destination's identifier (node id in
case of DAMOS_MIGRATE_*) and weight to the files.
Link: https://lkml.kernel.org/r/20250709005952.17776-4-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Bijan Tabatabai <bijantabatab@micron.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Add a new field to 'struct damos', namely migrate_dests, to allow DAMON
API callers specify multiple migration destination nodes and their
weights. Also update 'struct damos' creation and destruction functions
accordingly to initialize the new field and free up the API
caller-allocated buffers on those, respectively.
Link: https://lkml.kernel.org/r/20250709005952.17776-3-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/damon/vaddr: Allow interleaving in migrate_{hot,cold}
actions", v4.
A recent patchset automatically sets the interleave weight for each node
according to the node's maximum bandwidth [1]. In another thread, the
patch set's author, Joshua Hahn, wondered if/how thes weights should be
changed if the bandwidth utilization of the system changes [2].
This patch set adds the mechanism for dynamically changing how application
data is interleaved across nodes while leaving the policy of what the
interleave weights should be to userspace. It does this by having the
migrate_{hot,cold} operating schemes interleave application data according
to the list of migration nodes and weights passed in via the DAMON sysfs
interface. This functionality can be used to dynamically adjust how
folios are interleaved by having a userspace process adjust those weights.
If no specific destination nodes or weights are provided, the
migrate_{hot,cold} actions will only migrate folios to damos->target_nid
as before.
The algorithm used to interleave the folios is similar to the one used for
the weighted interleave mempolicy [3]. It uses the offset from which a
folio is mapped into a VMA to determine the node the folio should be
placed in. This method is convenient because for a given set of
interleave weights, a folio has only one valid node it can be placed in,
limitng the amount of unnecessary data movement. However, finding out how
a folio is mapped inside of a VMA requires a costly rmap walk when using a
paddr scheme. As such, we have decided that this functionality makes more
sense as a vaddr scheme [4]. To this end, this patch set also adds vaddr
versions of the migrate_{hot,cold}.
Motivation
==========
There have been prior discussions about how changing the interleave
weights in response to the system's bandwidth utilization can be
beneficial [2]. However, currently the interleave weights only are
applied when data is allocated. Migrating already allocated pages
according to the dynamically changing weights will better help balance the
bandwidth utilization across nodes.
As a toy example, imagine some application that uses 75% of the local
bandwidth. Assuming sufficient capacity, when running alone, we want to
keep that application's data in local memory. However, if a second
instance of that application begins, using the same amount of bandwidth,
it would be best to interleave the data of both processes to alleviate the
bandwidth pressure from the local node. Likewise, when one of the
processes ends, the data should be moves back to local memory.
We imagine there would be a userspace application that would monitor
system performance characteristics, such as bandwidth utilization or
memory access latency, and uses that information to tune the interleave
weights. Others seem to have come to a similar conclusion in previous
discussions [5]. We are currently working on a userspace program that
does this, but it is not quite ready to be published yet.
After the userspace application tunes the interleave weights, there must
be some mechanism that actually migrates pages to be consistent with those
weights. This patchset is what provides this mechanism.
We believe DAMON is the correct venue for the interleaving mechanism for a
few reasons. First, we noticed that we don't have to migrate all of the
application's pages to improve performance. we just need to migrate the
frequently accessed pages. DAMON's existing hotness traching is very
useful for this. Second, DAMON's quota system can be used to ensure we
are not using too much bandwidth for migrations. Finally, as Ying pointed
out [6], a complete solution must also handle when a memory node is at
capacity. The existing migrate_cold action can be used in conjunction
with the functionality added in this patch set to provide that complete
solution.
Functionality Test
==================
Below is an example of this new functionality in use to confirm that these
patches behave as intended.
In this example, the user starts an application, alloc_data, which
allocates 1GB using the default memory policy (i.e. allocate to local
memory) then sleeps. Afterwards, we start DAMON to interleave the data at
a 1:1 ratio. Using numastat, we show that DAMON has migrated the
application's data to match the new interleave ratio.
For this example, I modified the userspace damo tool [8] to write to the
migration_dest sysfs files. I plan to upstream these changes when these
patches are merged.
$ # Allocate the data initially
$ ./alloc_data 1G &
[1] 6587
$ numastat -c -p alloc_data
Per-node process memory usage (in MBs) for PID 6587 (alloc_data)
Node 0 Node 1 Total
------ ------ -----
Huge 0 0 0
Heap 0 0 0
Stack 0 0 0
Private 1027 0 1027
------- ------ ------ -----
Total 1027 0 1027
$ # Start DAMON to interleave data at a 1:1 ratio
$ cat ./interleave_vaddr.yaml
kdamonds:
- contexts:
- ops: vaddr
addr_unit: null
targets:
- pid: 6587
regions: []
intervals:
sample_us: 500 ms
aggr_us: 5 s
ops_update_us: 20 s
intervals_goal:
access_bp: 0 %
aggrs: '0'
min_sample_us: 0 ns
max_sample_us: 0 ns
nr_regions:
min: '20'
max: '50'
schemes:
- action: migrate_hot
dests:
- nid: 0
weight: 1
- nid: 1
weight: 1
access_pattern:
sz_bytes:
min: 0 B
max: max
nr_accesses:
min: 0 %
max: 100 %
age:
min: 0 ns
max: max
$ sudo ./damo/damo interleave_vaddr.yaml
$ # Verify that DAMON has migrated data to match the 1:1 ratio
$ numastat -c -p alloc_data
Per-node process memory usage (in MBs) for PID 6587 (alloc_data)
Node 0 Node 1 Total
------ ------ -----
Huge 0 0 0
Heap 0 0 0
Stack 0 0 0
Private 514 514 1027
------- ------ ------ -----
Total 514 514 1027
Performance Test
================
Below is a simple example showing that interleaving application data using
these patches can improve application performance. To do this, we run a
bandwidth intensive embedding reduction application [7]. This workload is
useful for this test because it reports the time it takes each iteration
to run and each iteration reuses the same allocation, allowing us to see
the benefits of the migration.
We evaluate this on a 128 core/256 thread AMD CPU with 72GB/s of local DDR
bandwidth and 26 GB/s of CXL bandwidth.
Before we start the workload, the system bandwidth utilization is low, so
we start with the interleave weights of 1:0, i.e. allocating all data to
local memory. When the workload beings, it saturates the local bandwidth,
making the page placement suboptimal. To alleviate this, we modify the
interleave weights, triggering DAMON to migrate the workload's data.
We use the same interleave_vaddr.yaml file to setup DAMON, except we
configure it to begin with a 1:0 interleave ratio, and attach it to the
shell and its children processes.
$ sudo ./damo/damo start interleave_vaddr.yaml --include_child_tasks &
$ <path>/eval_baseline -d amazon_All -c 255 -r 100
<clip startup output>
Eval Phase 3: Running Baseline...
REPEAT # 0 Baseline Total time : 7323.54 ms
REPEAT # 1 Baseline Total time : 7624.56 ms
REPEAT # 2 Baseline Total time : 7619.61 ms
REPEAT # 3 Baseline Total time : 7617.12 ms
REPEAT # 4 Baseline Total time : 7638.64 ms
REPEAT # 5 Baseline Total time : 7611.27 ms
REPEAT # 6 Baseline Total time : 7629.32 ms
REPEAT # 7 Baseline Total time : 7695.63 ms
# Interleave weights set to 3:1
REPEAT # 8 Baseline Total time : 7077.5 ms
REPEAT # 9 Baseline Total time : 5633.23 ms
REPEAT # 10 Baseline Total time : 5644.6 ms
REPEAT # 11 Baseline Total time : 5627.66 ms
REPEAT # 12 Baseline Total time : 5629.76 ms
REPEAT # 13 Baseline Total time : 5633.05 ms
REPEAT # 14 Baseline Total time : 5641.24 ms
REPEAT # 15 Baseline Total time : 5631.18 ms
REPEAT # 16 Baseline Total time : 5631.33 ms
Updating the interleave weights and having DAMON migrate the workload data
according to the weights resulted in an approximarely 25% speedup.
Patches Sequence
================
Patches 1-7 extend the DAMON API to specify multiple destination nodes and
weights for the migrate_{hot,cold} actions. These patches are from SJ'S
RFC [8].
Patches 8-10 add a vaddr implementation of the migrate_{hot,cold} schemes.
Patch 11 modifies the vaddr migrate_{hot,cold} schemes to interleave data
according to the weights provided by damos->migrate_dest.
Patches 12-13 allow the vaddr migrate_{hot,cold} implementation to filter
out folios like the paddr version.
This patch (of 13):
Introduce a new struct, namely damos_migrate_dests, for specifying
multiple DAMOS' migration destination nodes and their weights.
Link: https://lkml.kernel.org/r/20250709005952.17776-1-bijan311@gmail.com
Link: https://lkml.kernel.org/r/20250709005952.17776-2-bijan311@gmail.com
Link: https://lore.kernel.org/linux-mm/20250520141236.2987309-1-joshua.hahnjy@gmail.com/ [1]
Link: https://lore.kernel.org/linux-mm/20250313155705.1943522-1-joshua.hahnjy@gmail.com/ [2]
Link: https://elixir.bootlin.com/linux/v6.15.4/source/mm/mempolicy.c#L2015 [3]
Link: https://lore.kernel.org/damon/20250624223310.55786-1-sj@kernel.org/ [4]
Link: https://lore.kernel.org/linux-mm/20250314151137.892379-1-joshua.hahnjy@gmail.com/ [5]
Link: https://lore.kernel.org/linux-mm/87frjfx6u4.fsf@DESKTOP-5N7EMDA/ [6]
Link: https://github.com/SNU-ARC/MERCI [7]
Link: https://lore.kernel.org/damon/20250702051558.54138-1-sj@kernel.org/ [8]
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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