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Hou Tao says: ==================== From: Hou Tao <houtao1@huawei.com> Hi, The patchset aims to fix the issues found during investigating the syzkaller problem reported in [0]. It seems that the concurrent updates to the same hash-table bucket may fail as shown in patch 1. Patch 1 uses preempt_disable() to fix the problem for htab_use_raw_lock() case. For !htab_use_raw_lock() case, the problem is left to "BPF specific memory allocator" patchset [1] in which !htab_use_raw_lock() will be removed. Patch 2 fixes the out-of-bound memory read problem reported in [0]. The problem has the root cause as patch 1 and it is fixed by handling -EBUSY from htab_lock_bucket() correctly. Patch 3 add two cases for hash-table update: one for the reentrancy of bpf_map_update_elem(), and another one for concurrent updates of the same hash-table bucket. Comments are always welcome. Regards, Tao [0]: https://lore.kernel.org/bpf/CACkBjsbuxaR6cv0kXJoVnBfL9ZJXjjoUcMpw_Ogc313jSrg14A@mail.gmail.com/ [1]: https://lore.kernel.org/bpf/20220819214232.18784-1-alexei.starovoitov@gmail.com/ Change Log: v4: * rebased on bpf-next * add htab_update to DENYLIST.s390x v3: https://lore.kernel.org/bpf/20220829023709.1958204-1-houtao@huaweicloud.com/ * patch 1: update commit message and add Fixes tag * patch 2: add Fixes tag * patch 3: elaborate the description of test cases v2: https://lore.kernel.org/bpf/bd60ef93-1c6a-2db2-557d-b09b92ad22bd@huaweicloud.com/ * Note the fix is for CONFIG_PREEMPT case in commit message and add Reviewed-by tag for patch 1 * Drop patch "bpf: Allow normally concurrent map updates for !htab_use_raw_lock() case" v1: https://lore.kernel.org/bpf/20220821033223.2598791-1-houtao@huaweicloud.com/ ==================== Signed-off-by: Martin KaFai Lau <martin.lau@kernel.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.