b243dcbf2f
Patch series "Per-VMA lock support for swap and userfaults", v7.
When per-VMA locks were introduced in [1] several types of page faults
would still fall back to mmap_lock to keep the patchset simple. Among
them are swap and userfault pages. The main reason for skipping those
cases was the fact that mmap_lock could be dropped while handling these
faults and that required additional logic to be implemented. Implement
the mechanism to allow per-VMA locks to be dropped for these cases.
First, change handle_mm_fault to drop per-VMA locks when returning
VM_FAULT_RETRY or VM_FAULT_COMPLETED to be consistent with the way
mmap_lock is handled. Then change folio_lock_or_retry to accept vm_fault
and return vm_fault_t which simplifies later patches. Finally allow swap
and uffd page faults to be handled under per-VMA locks by dropping per-VMA
and retrying, the same way it's done under mmap_lock. Naturally, once VMA
lock is dropped that VMA should be assumed unstable and can't be used.
This patch (of 6):
Commit [1] introduced IO polling support duding swapin to reduce swap read
latency for block devices that can be polled. However later commit [2]
removed polling support. Therefore it seems safe to remove do_poll
parameter in read_swap_cache_async and always call swap_readpage with
synchronous=false waiting for IO completion in folio_lock_or_retry.
[1] commit 23955622ff8d ("swap: add block io poll in swapin path")
[2] commit 9650b453a3d4 ("block: ignore RWF_HIPRI hint for sync dio")
Link: https://lkml.kernel.org/r/20230630211957.1341547-1-surenb@google.com
Link: https://lkml.kernel.org/r/20230630211957.1341547-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@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.