b6769834aa
lru_lock and page cache xa_lock have no obvious reason to be taken one way round or the other: until now, lru_lock has been taken before page cache xa_lock, when splitting a THP; but nothing else takes them together. Reverse that ordering: let's narrow the lru locking - but leave local_irq_disable to block interrupts throughout, like before. Hugh Dickins point: split_huge_page_to_list() was already silly, to be using the _irqsave variant: it's just been taking sleeping locks, so would already be broken if entered with interrupts enabled. So we can save passing flags argument down to __split_huge_page(). Why change the lock ordering here? That was hard to decide. One reason: when this series reaches per-memcg lru locking, it relies on the THP's memcg to be stable when taking the lru_lock: that is now done after the THP's refcount has been frozen, which ensures page memcg cannot change. Another reason: previously, lock_page_memcg()'s move_lock was presumed to nest inside lru_lock; but now lru_lock must nest inside (page cache lock inside) move_lock, so it becomes possible to use lock_page_memcg() to stabilize page memcg before taking its lru_lock. That is not the mechanism used in this series, but it is an option we want to keep open. [hughd@google.com: rewrite commit log] Link: https://lkml.kernel.org/r/1604566549-62481-5-git-send-email-alex.shi@linux.alibaba.com Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Chen, Rong A" <rong.a.chen@intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.