docs(fast_io): document mmap page-fault impact on io_uring SQPOLL (#1661)#3493
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) Documents the hazard that arises when IORING_SETUP_SQPOLL is enabled and SQEs reference mmap'd basis-file pages that are not yet resident: the kthread context cannot service major page faults the way a userspace task can, leading to stalls, fall-back to task-work, or -EFAULT completions. Companion to docs/audits/mmap-iouring-co-usage.md (#3440). Records the constraint so that whoever wires SQPOLL prefaults or avoids mmap on the basis side first. Salvaged from worktree branch docs/mmap-page-fault-sqpoll.
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) (#3493) Documents the hazard that arises when IORING_SETUP_SQPOLL is enabled and SQEs reference mmap'd basis-file pages that are not yet resident: the kthread context cannot service major page faults the way a userspace task can, leading to stalls, fall-back to task-work, or -EFAULT completions. Companion to docs/audits/mmap-iouring-co-usage.md (#3440). Records the constraint so that whoever wires SQPOLL prefaults or avoids mmap on the basis side first. Salvaged from worktree branch docs/mmap-page-fault-sqpoll.
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Summary
docs/audits/mmap-page-fault-iouring-sqpoll.mdCloses #1661. Companion to #3440 (mmap + io_uring co-usage audit).
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