On Mon, Apr 25, 2022 at 10:31:12AM -0400, Zi Yan wrote: > From: Zi Yan <ziy@xxxxxxxxxx> > > Hi David, > > This patchset tries to remove the MAX_ORDER-1 alignment requirement for CMA > and alloc_contig_range(). It prepares for my upcoming changes to make > MAX_ORDER adjustable at boot time[1]. It is on top of mmotm-2022-04-20-17-12. > > Changelog > === > V11 > --- > 1. Moved start_isolate_page_range()/undo_isolate_page_range() alignment > change to a separate patch after the unmovable page check change and > alloc_contig_range() change to avoid some unwanted memory > hotplug/hotremove failures. > 2. Cleaned up has_unmovable_pages() in Patch 2. > > V10 > --- > 1. Reverted back to the original outer_start, outer_end range for > test_pages_isolated() and isolate_freepages_range() in Patch 3, > otherwise isolation will fail if start in alloc_contig_range() is in > the middle of a free page. > > V9 > --- > 1. Limited has_unmovable_pages() check within a pageblock. > 2. Added a check to ensure page isolation is done within a single zone > in isolate_single_pageblock(). > 3. Fixed an off-by-one bug in isolate_single_pageblock(). > 4. Fixed a NULL-deferencing bug when the pages before to-be-isolated pageblock > is not online in isolate_single_pageblock(). > > V8 > --- > 1. Cleaned up has_unmovable_pages() to remove page argument. > > V7 > --- > 1. Added page validity check in isolate_single_pageblock() to avoid out > of zone pages. > 2. Fixed a bug in split_free_page() to split and free pages in correct > page order. > > V6 > --- > 1. Resolved compilation error/warning reported by kernel test robot. > 2. Tried to solve the coding concerns from Christophe Leroy. > 3. Shortened lengthy lines (pointed out by Christoph Hellwig). > > V5 > --- > 1. Moved isolation address alignment handling in start_isolate_page_range(). > 2. Rewrote and simplified how alloc_contig_range() works at pageblock > granularity (Patch 3). Only two pageblock migratetypes need to be saved and > restored. start_isolate_page_range() might need to migrate pages in this > version, but it prevents the caller from worrying about > max(MAX_ORDER_NR_PAEGS, pageblock_nr_pages) alignment after the page range > is isolated. > > V4 > --- > 1. Dropped two irrelevant patches on non-lru compound page handling, as > it is not supported upstream. > 2. Renamed migratetype_has_fallback() to migratetype_is_mergeable(). > 3. Always check whether two pageblocks can be merged in > __free_one_page() when order is >= pageblock_order, as the case (not > mergeable pageblocks are isolated, CMA, and HIGHATOMIC) becomes more common. > 3. Moving has_unmovable_pages() is now a separate patch. > 4. Removed MAX_ORDER-1 alignment requirement in the comment in virtio_mem code. > > Description > === > > The MAX_ORDER - 1 alignment requirement comes from that alloc_contig_range() > isolates pageblocks to remove free memory from buddy allocator but isolating > only a subset of pageblocks within a page spanning across multiple pageblocks > causes free page accounting issues. Isolated page might not be put into the > right free list, since the code assumes the migratetype of the first pageblock > as the whole free page migratetype. This is based on the discussion at [2]. > > To remove the requirement, this patchset: > 1. isolates pages at pageblock granularity instead of > max(MAX_ORDER_NR_PAEGS, pageblock_nr_pages); > 2. splits free pages across the specified range or migrates in-use pages > across the specified range then splits the freed page to avoid free page > accounting issues (it happens when multiple pageblocks within a single page > have different migratetypes); > 3. only checks unmovable pages within the range instead of MAX_ORDER - 1 aligned > range during isolation to avoid alloc_contig_range() failure when pageblocks > within a MAX_ORDER - 1 aligned range are allocated separately. > 4. returns pages not in the range as it did before. > > One optimization might come later: > 1. make MIGRATE_ISOLATE a separate bit to be able to restore the original > migratetypes when isolation fails in the middle of the range. > > Feel free to give comments and suggestions. Thanks. > > [1] https://lore.kernel.org/linux-mm/20210805190253.2795604-1-zi.yan@xxxxxxxx/ > [2] https://lore.kernel.org/linux-mm/d19fb078-cb9b-f60f-e310-fdeea1b947d2@xxxxxxxxxx/ > > Zi Yan (6): > mm: page_isolation: move has_unmovable_pages() to mm/page_isolation.c > mm: page_isolation: check specified range for unmovable pages > mm: make alloc_contig_range work at pageblock granularity > mm: page_isolation: enable arbitrary range page isolation. > mm: cma: use pageblock_order as the single alignment > drivers: virtio_mem: use pageblock size as the minimum virtio_mem > size. > > drivers/virtio/virtio_mem.c | 6 +- > include/linux/cma.h | 4 +- > include/linux/mmzone.h | 5 +- > include/linux/page-isolation.h | 6 +- > mm/internal.h | 6 + > mm/memory_hotplug.c | 3 +- > mm/page_alloc.c | 191 +++++------------- > mm/page_isolation.c | 345 +++++++++++++++++++++++++++++++-- > 8 files changed, 392 insertions(+), 174 deletions(-) Reverting this series fixed a deadlock during memory offline/online tests and then a crash. INFO: task kmemleak:1027 blocked for more than 120 seconds. Not tainted 5.18.0-rc4-next-20220426-dirty #27 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kmemleak state:D stack:27744 pid: 1027 ppid: 2 flags:0x00000008 Call trace: __switch_to __schedule schedule percpu_rwsem_wait __percpu_down_read percpu_down_read.constprop.0 get_online_mems kmemleak_scan kmemleak_scan_thread kthread ret_from_fork Showing all locks held in the system: 1 lock held by rcu_tasks_kthre/11: #0: ffffc1e2cefc17f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp 1 lock held by rcu_tasks_rude_/12: #0: ffffc1e2cefc1a90 (rcu_tasks_rude.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp 1 lock held by rcu_tasks_trace/13: #0: ffffc1e2cefc1db0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp 1 lock held by khungtaskd/824: #0: ffffc1e2cefc2820 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks 2 locks held by kmemleak/1027: #0: ffffc1e2cf1aa628 (scan_mutex){+.+.}-{3:3}, at: kmemleak_scan_thread #1: ffffc1e2cf14e690 (mem_hotplug_lock){++++}-{0:0}, at: get_online_mems 2 locks held by cppc_fie/1805: 1 lock held by in:imklog/2822: 8 locks held by tee/3334: #0: ffff0816d65c9438 (sb_writers#6){.+.+}-{0:0}, at: vfs_write #1: ffff40025438be88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter #2: ffff4000c8261eb0 (kn->active#298){.+.+}-{0:0}, at: kernfs_fop_write_iter #3: ffffc1e2d0013f68 (device_hotplug_lock){+.+.}-{3:3}, at: online_store #4: ffff0800cd8bb998 (&dev->mutex){....}-{3:3}, at: device_offline #5: ffffc1e2ceed3750 (cpu_hotplug_lock){++++}-{0:0}, at: cpus_read_lock #6: ffffc1e2cf14e690 (mem_hotplug_lock){++++}-{0:0}, at: offline_pages #7: ffffc1e2cf13bf68 (pcp_batch_high_lock){+.+.}-{3:3}, at: zone_pcp_disable __zone_set_pageset_high_and_batch at mm/page_alloc.c:7005 (inlined by) zone_pcp_disable at mm/page_alloc.c:9286 Later, running some kernel compilation workloads could trigger a crash. Unable to handle kernel paging request at virtual address fffffbfffe000030 KASAN: maybe wild-memory-access in range [0x0003dffff0000180-0x0003dffff0000187] Mem abort info: ESR = 0x96000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x06: level 2 translation fault Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000817545fd000 [fffffbfffe000030] pgd=00000817581e9003, p4d=00000817581e9003, pud=00000817581ea003, pmd=0000000000000000 Internal error: Oops: 96000006 [#1] PREEMPT SMP Modules linked in: bridge stp llc cdc_ether usbnet ipmi_devintf ipmi_msghandler cppc_cpufreq fuse ip_tables x_tables ipv6 btrfs blake2b_generic libcrc32c xor xor_neon raid6_pq zstd_compress dm_mod nouveau drm_ttm_helper ttm crct10dif_ce mlx5_core drm_display_helper drm_kms_helper nvme mpt3sas xhci_pci nvme_core drm raid_class xhci_pci_renesas CPU: 147 PID: 3334 Comm: tee Not tainted 5.18.0-rc4-next-20220426-dirty #27 pstate: 10400009 (nzcV daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : isolate_single_pageblock lr : isolate_single_pageblock sp : ffff80003e767500 x29: ffff80003e767500 x28: 0000000000000000 x27: ffff783c59963b1f x26: dfff800000000000 x25: ffffc1e2ccb1d000 x24: ffffc1e2ccb1d8f8 x23: 00000000803bfe00 x22: ffffc1e2cee39098 x21: 0000000000000020 x20: 00000000803c0000 x19: fffffbfffe000000 x18: ffffc1e2cee37d1c x17: 0000000000000000 x16: 1fffe8004a86f14c x15: 1fffe806c89e154a x14: 1fffe8004a86f11c x13: 0000000000000004 x12: ffff783c5c455e6d x11: 1ffff83c5c455e6c x10: ffff783c5c455e6c x9 : dfff800000000000 x8 : ffffc1e2e22af363 x7 : 0000000000000001 x6 : 0000000000000003 x5 : ffffc1e2e22af360 x4 : ffff783c5c455e6c x3 : ffff700007cece90 x2 : 0000000000000003 x1 : 0000000000000000 x0 : fffffbfffe000030 Call trace: Call trace: isolate_single_pageblock PageBuddy at ./include/linux/page-flags.h:969 (discriminator 3) (inlined by) isolate_single_pageblock at mm/page_isolation.c:414 (discriminator 3) start_isolate_page_range offline_pages memory_subsys_offline device_offline online_store dev_attr_store sysfs_kf_write kernfs_fop_write_iter new_sync_write vfs_write ksys_write __arm64_sys_write invoke_syscall el0_svc_common.constprop.0 do_el0_svc el0_svc el0t_64_sync_handler el0t_64_sync Code: 38fa6821 7100003f 7a411041 54000dca (b9403260) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception SMP: stopping secondary CPUs Kernel Offset: 0x41e2c0720000 from 0xffff800008000000 PHYS_OFFSET: 0x80000000 CPU features: 0x000,0021700d,19801c82 Memory Limit: none
