Messages in this thread | | | Date | Mon, 19 May 2014 22:59:15 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm/vmscan: Do not block forever at shrink_inactive_list(). |
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On Tue, 20 May 2014 10:44:49 +1000 Dave Chinner <david@fromorbit.com> wrote:
> @@ -258,14 +258,23 @@ xfs_bmapi_allocate_worker( > struct xfs_bmalloca *args = container_of(work, > struct xfs_bmalloca, work); > unsigned long pflags; > + unsigned long new_pflags = PF_FSTRANS; > > - /* we are in a transaction context here */ > - current_set_flags_nested(&pflags, PF_FSTRANS); > + /* > + * we are in a transaction context here, but may also be doing work > + * in kswapd context, and hence we may need to inherit that state > + * temporarily to ensure that we don't block waiting for memory reclaim > + * in any way. > + */ > + if (args->kswapd) > + new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
So current_is_kswapd() returns true for a thread which is not kswapd. That's a bit smelly.
Should this thread really be incrementing KSWAPD_INODESTEAL instead of PGINODESTEAL, for example? current_is_kswapd() does a range of things, only one(?) of which you actually want.
It would be cleaner to create a new PF_ flag to select just that behavior. That's a better model than telling the world "I am magic and special".
But we're awfully close to running out of PF_ space and I don't know if this ugly justifies consuming a flag.
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