Minimal supplement to upstream Kernel Self Protection Project changes. Features already provided by SELinux + Yama and archs other than multiarch arm64 / x86_64 aren't in scope. Only tags have stable history. Shared IRC channel with KSPP: irc.libera.chat #linux-hardening
13c931bd9a
This commit fixes a bug triggered by a non-trivial sequence of events. These events are briefly described in the next two paragraphs. The impatiens, or those who are familiar with queue merging and splitting, can jump directly to the last paragraph. On each I/O-request arrival for a shared bfq_queue, i.e., for a bfq_queue that is the result of the merge of two or more bfq_queues, BFQ checks whether the shared bfq_queue has become seeky (i.e., if too many random I/O requests have arrived for the bfq_queue; if the device is non rotational, then random requests must be also small for the bfq_queue to be tagged as seeky). If the shared bfq_queue is actually detected as seeky, then a split occurs: the bfq I/O context of the process that has issued the request is redirected from the shared bfq_queue to a new non-shared bfq_queue. As a degenerate case, if the shared bfq_queue actually happens to be shared only by one process (because of previous splits), then no new bfq_queue is created: the state of the shared bfq_queue is just changed from shared to non shared. Regardless of whether a brand new non-shared bfq_queue is created, or the pre-existing shared bfq_queue is just turned into a non-shared bfq_queue, several parameters of the non-shared bfq_queue are set (restored) to the original values they had when the bfq_queue associated with the bfq I/O context of the process (that has just issued an I/O request) was merged with the shared bfq_queue. One of these parameters is the weight-raising state. If, on the split of a shared bfq_queue, 1) a pre-existing shared bfq_queue is turned into a non-shared bfq_queue; 2) the previously shared bfq_queue happens to be busy; 3) the weight-raising state of the previously shared bfq_queue happens to change; the number of weight-raised busy queues changes. The field wr_busy_queues must then be updated accordingly, but such an update was missing. This commit adds the missing update. Reported-by: Luca Miccio <lucmiccio@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.