Messages in this thread | | | Date | Mon, 4 May 2020 13:04:51 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free_percpu() |
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On Mon, 4 May 2020 11:38:43 -0400 (EDT) Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> ----- 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. >
It doesn't surprise me because my alloc_percpu() call never gets to that path. But systemd does hit it for me earlier on.
-- Steve
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