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    SubjectRe: [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free_percpu()
    ----- On May 4, 2020, at 11:31 AM, Joerg Roedel jroedel@suse.de wrote:

    > On Mon, May 04, 2020 at 11:28:46AM -0400, Mathieu Desnoyers wrote:
    >> ----- On May 4, 2020, at 11:12 AM, Joerg Roedel jroedel@suse.de wrote:
    >> Placing this here is inefficient. It syncs mappings for each percpu allocation.
    >> I would recommend moving it right after __vmalloc() is called to allocate the
    >> underlying memory chunk instead:
    >>
    >> static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
    >> {
    >
    > Tried this before, actually I put it into the caller of
    > pcpu_mem_zalloc(), but that didn't fix the problem for me. Stevens
    > test-case still hangs the machine.

    That's unexpected.

    Did you confirm that those hangs were also caused by percpu allocations ?

    Maybe adding the vmalloc_sync_mappings() at each percpu allocation happens
    to luckily sync mappings after some other vmalloc.

    Thanks,

    Mathieu


    --
    Mathieu Desnoyers
    EfficiOS Inc.
    http://www.efficios.com

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