928130532e
offline_pages() properly checks for memory holes and bails out. However, we do a page_zone(pfn_to_page(start_pfn)) before calling offline_pages() when offlining a memory block. We should not unconditionally call page_zone(pfn_to_page(start_pfn)) on aarch64 in offlining code, otherwise we can trigger a BUG when hitting a memory hole: kernel BUG at include/linux/mm.h:1383! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: loop processor efivarfs ip_tables x_tables ext4 mbcache jbd2 dm_mod igb nvme i2c_algo_bit mlx5_core i2c_core nvme_core firmware_class CPU: 13 PID: 1694 Comm: ranbug Not tainted 5.12.0-next-20210524+ #4 Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020 pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) pc : memory_subsys_offline+0x1f8/0x250 lr : memory_subsys_offline+0x1f8/0x250 Call trace: memory_subsys_offline+0x1f8/0x250 device_offline+0x154/0x1d8 online_store+0xa4/0x118 dev_attr_store+0x44/0x78 sysfs_kf_write+0xe8/0x138 kernfs_fop_write_iter+0x26c/0x3d0 new_sync_write+0x2bc/0x4f8 vfs_write+0x718/0xc88 ksys_write+0xf8/0x1e0 __arm64_sys_write+0x74/0xa8 invoke_syscall.constprop.0+0x78/0x1e8 do_el0_svc+0xe4/0x298 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb8 el0_sync+0x178/0x180 Kernel panic - not syncing: Oops - BUG: Fatal exception SMP: stopping secondary CPUs Kernel Offset: disabled CPU features: 0x00000251,20000846 Memory Limit: none If nr_vmemmap_pages is set, we know that we are dealing with hotplugged memory that doesn't have any holes. So call page_zone(pfn_to_page(start_pfn)) only when really necessary -- when nr_vmemmap_pages is set and we actually adjust the present pages. Link: https://lkml.kernel.org/r/20210526075226.5572-1-david@redhat.com Fixes: a08a2ae34613 ("mm,memory_hotplug: allocate memmap from the added memory range") Signed-off-by: David Hildenbrand <david@redhat.com> Reported-by: Qian Cai (QUIC) <quic_qiancai@quicinc.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Mike Rapoport <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.