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Patch series "Make MIGRATE_ISOLATE a standalone bit", v10.
This patchset moves MIGRATE_ISOLATE to a standalone bit to avoid being
overwritten during pageblock isolation process. Currently,
MIGRATE_ISOLATE is part of enum migratetype (in include/linux/mmzone.h),
thus, setting a pageblock to MIGRATE_ISOLATE overwrites its original
migratetype. This causes pageblock migratetype loss during
alloc_contig_range() and memory offline, especially when the process fails
due to a failed pageblock isolation and the code tries to undo the
finished pageblock isolations.
In terms of performance for changing pageblock types, no performance
change is observed:
1. I used perf to collect stats of offlining and onlining all memory
of a 40GB VM 10 times and see that get_pfnblock_flags_mask() and
set_pfnblock_flags_mask() take about 0.12% and 0.02% of the whole
process respectively with and without this patchset across 3 runs.
2. I used perf to collect stats of dd from /dev/random to a 40GB tmpfs
file and find get_pfnblock_flags_mask() takes about 0.05% of the
process with and without this patchset across 3 runs.
This patch (of 6):
No functional change is intended.
1. Add __NR_PAGEBLOCK_BITS for the number of pageblock flag bits and use
roundup_pow_of_two(__NR_PAGEBLOCK_BITS) as NR_PAGEBLOCK_BITS to take
right amount of bits for pageblock flags.
2. Rename PB_migrate_skip to PB_compact_skip.
3. Add {get,set,clear}_pfnblock_bit() to operate one a standalone bit,
like PB_compact_skip.
3. Make {get,set}_pfnblock_flags_mask() internal functions and use
{get,set}_pfnblock_migratetype() for pageblock migratetype operations.
4. Move pageblock flags common code to get_pfnblock_bitmap_bitidx().
3. Use MIGRATETYPE_MASK to get the migratetype of a pageblock from its
flags.
4. Use PB_migrate_end in the definition of MIGRATETYPE_MASK instead of
PB_migrate_bits.
5. Add a comment on is_migrate_cma_folio() to prevent one from changing it
to use get_pageblock_migratetype() and causing issues.
Link: https://lkml.kernel.org/r/20250617021115.2331563-1-ziy@nvidia.com
Link: https://lkml.kernel.org/r/20250617021115.2331563-2-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Richard Chang <richardycc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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| ABI | ||
| accel | ||
| accounting | ||
| admin-guide | ||
| arch | ||
| block | ||
| bpf | ||
| cdrom | ||
| core-api | ||
| cpu-freq | ||
| crypto | ||
| dev-tools | ||
| devicetree | ||
| doc-guide | ||
| driver-api | ||
| edac | ||
| fault-injection | ||
| fb | ||
| features | ||
| filesystems | ||
| firmware_class | ||
| firmware-guide | ||
| fpga | ||
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| hwmon | ||
| i2c | ||
| iio | ||
| images | ||
| infiniband | ||
| input | ||
| isdn | ||
| kbuild | ||
| kernel-hacking | ||
| leds | ||
| litmus-tests | ||
| livepatch | ||
| locking | ||
| maintainer | ||
| mhi | ||
| misc-devices | ||
| mm | ||
| netlabel | ||
| netlink | ||
| networking | ||
| nvdimm | ||
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| PCI | ||
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| peci | ||
| power | ||
| process | ||
| RCU | ||
| rust | ||
| scheduler | ||
| scsi | ||
| security | ||
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| sphinx | ||
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| staging | ||
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| target | ||
| tee | ||
| timers | ||
| tools | ||
| trace | ||
| translations | ||
| usb | ||
| userspace-api | ||
| virt | ||
| w1 | ||
| watchdog | ||
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| .gitignore | ||
| atomic_bitops.txt | ||
| atomic_t.txt | ||
| Changes | ||
| CodingStyle | ||
| conf.py | ||
| docutils.conf | ||
| index.rst | ||
| Kconfig | ||
| Makefile | ||
| memory-barriers.txt | ||
| SubmittingPatches | ||
| subsystem-apis.rst | ||