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John reports that the recently merged commit1a8e1cef76("arm64: use both ZONE_DMA and ZONE_DMA32") breaks the boot on his DB845C board: | Booting Linux on physical CPU 0x0000000000 [0x517f803c] | Linux version 5.4.0-mainline-10675-g957a03b9e38f | Machine model: Thundercomm Dragonboard 845c | [...] | Built 1 zonelists, mobility grouping on. Total pages: -188245 | Kernel command line: earlycon | firmware_class.path=/vendor/firmware/ androidboot.hardware=db845c | init=/init androidboot.boot_devices=soc/1d84000.ufshc | printk.devkmsg=on buildvariant=userdebug root=/dev/sda2 | androidboot.bootdevice=1d84000.ufshc androidboot.serialno=c4e1189c | androidboot.baseband=sda | msm_drm.dsi_display0=dsi_lt9611_1080_video_display: | androidboot.slot_suffix=_a skip_initramfs rootwait ro init=/init | | <hangs indefinitely here> This is because, when CONFIG_NUMA=n, zone_sizes_init() fails to handle memblocks that fall entirely within the ZONE_DMA region and erroneously ends up trying to add a negatively-sized region into the following ZONE_DMA32, which is later interpreted as a large unsigned region by the core MM code. Rework the non-NUMA implementation of zone_sizes_init() so that the start address of the memblock being processed is adjusted according to the end of the previous zone, which is then range-checked before updating the hole information of subsequent zones. Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/lkml/CALAqxLVVcsmFrDKLRGRq7GewcW405yTOxG=KR3csVzQ6bXutkA@mail.gmail.com Fixes:1a8e1cef76("arm64: use both ZONE_DMA and ZONE_DMA32") Reported-by: John Stultz <john.stultz@linaro.org> Tested-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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.