From: Andrea Arcangeli <aarcange@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan.kim@gmail.com>,
Michel Lespinasse <walken@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Hugh Dickins <hughd@google.com>,
Johannes Weiner <jweiner@redhat.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Shaohua Li <shaohua.li@intel.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: thp: gup_fast ppc tail refcounting [was Re: [PATCH] thp: tail page refcounting fix #6]
Date: Sun, 16 Oct 2011 22:37:01 +0200 [thread overview]
Message-ID: <1318797426-26600-1-git-send-email-aarcange@redhat.com> (raw)
In-Reply-To: <1316793432.9084.47.camel@twins>
Hi everyone,
so I reviewed the ppc gup_fast hugetlbfs code a bit, fixed the
longstanding memory corrupting bugs (could trigger if mmremap
functions run under gup_fast) and I fixed the code that was supposed
to make it work with thp introduction in 2.6.38 and more recently with
the tail refcounting race fixes in -mm. This is incremental with the
thp refcoutning race fixes merged in -mm.
To me those rollbacking if the pte changed that ppc is doing looks
unnecessary, the speculative access also looks unnecessary (there is
no way the page_count of the head or regular pages can be zero
there). x86 doesn't do any specualtive refcounting and it won't care
if the pte changed (we know the page can't go away from under us
because irqs are disabled). If tlb flushing code works on ppc like x86
there should be no need of that.
However I didn't remove those two rollback conditions, in theory it
shouldn't hurt (well not anymore, after fixing the two corrupting
bugs...). I just tried to make the minimal changes required because I
didn't test it. It'd be nice if ppc users could test it with O_DIRECT
on top of hugetlbfs and report if this works. I build-tested it
though, so it should build just fine at least.
s390x should be the only other arch that needs revisiting to make
gup_fast + hugetlbfs to work properly. I'll do that next.
[PATCH 1/4] powerpc: remove superfluous PageTail checks on the pte gup_fast
[PATCH 2/4] powerpc: get_hugepte() don't put_page() the wrong page
[PATCH 3/4] powerpc: gup_hugepte() avoid to free the head page too many times
[PATCH 4/4] powerpc: gup_hugepte() support THP based tail recounting
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next prev parent reply other threads:[~2011-10-16 20:38 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-19 7:48 [PATCH 0/9] Use RCU to stabilize page counts Michel Lespinasse
2011-08-19 7:48 ` [PATCH 1/9] mm: rcu read lock for getting reference on pages in migration_entry_wait() Michel Lespinasse
2011-08-19 7:48 ` [PATCH 2/9] mm: avoid calling get_page_unless_zero() when charging cgroups Michel Lespinasse
2011-08-19 7:48 ` [PATCH 3/9] mm: rcu read lock when getting from tail to head page Michel Lespinasse
2011-08-19 7:48 ` [PATCH 4/9] mm: use get_page in deactivate_page() Michel Lespinasse
2011-08-19 7:48 ` [PATCH 5/9] kvm: use get_page instead of get_page_unless_zero Michel Lespinasse
2011-08-19 7:48 ` [PATCH 6/9] mm: assert that get_page_unless_zero() callers hold the rcu lock Michel Lespinasse
2011-08-19 23:28 ` Andi Kleen
2011-08-19 7:48 ` [PATCH 7/9] rcu: rcu_get_gp_cookie() / rcu_gp_cookie_elapsed() stand-ins Michel Lespinasse
2011-08-19 7:48 ` [PATCH 8/9] mm: add API for setting a grace period cookie on compound pages Michel Lespinasse
2011-08-19 7:48 ` [PATCH 9/9] mm: make sure tail page counts are stable before splitting THP pages Michel Lespinasse
2011-08-19 7:53 ` [PATCH 0/9] Use RCU to stabilize page counts Michel Lespinasse
2011-08-22 21:33 ` [PATCH] thp: tail page refcounting fix Andrea Arcangeli
2011-08-23 14:55 ` Andrea Arcangeli
2011-08-23 16:45 ` Minchan Kim
2011-08-23 16:54 ` Andrea Arcangeli
2011-08-23 19:52 ` Michel Lespinasse
2011-08-24 0:09 ` Andrea Arcangeli
2011-08-24 0:27 ` Andrea Arcangeli
2011-08-24 13:34 ` [PATCH] thp: tail page refcounting fix #2 Andrea Arcangeli
2011-08-26 6:24 ` Michel Lespinasse
2011-08-26 16:10 ` Andrea Arcangeli
2011-08-26 18:54 ` [PATCH] thp: tail page refcounting fix #3 Andrea Arcangeli
2011-08-27 9:41 ` Michel Lespinasse
2011-08-27 17:34 ` [PATCH] thp: tail page refcounting fix #4 Andrea Arcangeli
2011-08-29 4:20 ` Minchan Kim
2011-09-01 15:24 ` [PATCH] thp: tail page refcounting fix #5 Andrea Arcangeli
2011-09-01 22:27 ` Michel Lespinasse
2011-09-01 23:28 ` Andrew Morton
2011-09-01 23:45 ` Andi Kleen
2011-09-02 0:20 ` Andrea Arcangeli
2011-09-02 1:17 ` Andi Kleen
2011-09-02 0:03 ` Andrew Morton
2011-09-08 16:51 ` [PATCH] thp: tail page refcounting fix #6 Andrea Arcangeli
2011-09-23 15:57 ` Peter Zijlstra
2011-09-30 13:58 ` Andrea Arcangeli
2011-10-16 20:37 ` Andrea Arcangeli [this message]
2011-10-16 20:37 ` [PATCH 1/4] powerpc: remove superfluous PageTail checks on the pte gup_fast Andrea Arcangeli
2011-10-16 20:37 ` [PATCH 2/4] powerpc: get_hugepte() don't put_page() the wrong page Andrea Arcangeli
2011-10-16 20:37 ` [PATCH 3/4] powerpc: gup_hugepte() avoid to free the head page too many times Andrea Arcangeli
2011-10-16 20:37 ` [PATCH 4/4] powerpc: gup_hugepte() support THP based tail recounting Andrea Arcangeli
2011-10-16 20:40 ` thp: gup_fast ppc tail refcounting [was Re: [PATCH] thp: tail page refcounting fix #6] Andrea Arcangeli
2011-10-16 20:40 ` [PATCH 1/4] powerpc: remove superfluous PageTail checks on the pte gup_fast Andrea Arcangeli
2011-10-16 20:40 ` [PATCH 2/4] powerpc: get_hugepte() don't put_page() the wrong page Andrea Arcangeli
2011-10-16 20:40 ` [PATCH 3/4] powerpc: gup_hugepte() avoid to free the head page too many times Andrea Arcangeli
2011-10-16 20:40 ` [PATCH 4/4] powerpc: gup_hugepte() support THP based tail recounting Andrea Arcangeli
2011-10-17 14:41 ` thp: gup_fast s390/sparc tail refcounting [was Re: [PATCH] thp: tail page refcounting fix #6] Andrea Arcangeli
2011-10-17 14:41 ` [PATCH 1/3] s390: gup_huge_pmd() support THP tail recounting Andrea Arcangeli
2011-10-17 14:41 ` [PATCH 2/3] sparc: gup_pte_range() support THP based " Andrea Arcangeli
2011-10-17 22:44 ` David Miller
2011-10-17 14:41 ` [PATCH 3/3] thp: share get_huge_page_tail() Andrea Arcangeli
2011-10-17 21:32 ` fix two more s390/sparc gup_fast bugs Andrea Arcangeli
2011-10-17 21:32 ` [PATCH 1/2] s390: gup_huge_pmd() return 0 if pte changes Andrea Arcangeli
2011-10-17 21:32 ` [PATCH 2/2] powerpc: " Andrea Arcangeli
2011-08-29 22:40 ` [PATCH] thp: tail page refcounting fix #4 Michel Lespinasse
2011-08-29 23:30 ` Andrea Arcangeli
2011-08-26 19:28 ` [PATCH] thp: tail page refcounting fix #2 Andrea Arcangeli
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