mm: introduce ->swap_rw and use it for reads from SWP_FS_OPS swap-space

swap currently uses ->readpage to read swap pages. This can only request
one page at a time from the filesystem, which is not

mm: introduce ->swap_rw and use it for reads from SWP_FS_OPS swap-space

swap currently uses ->readpage to read swap pages. This can only request
one page at a time from the filesystem, which is not most efficient.

swap uses ->direct_IO for writes which while this is adequate is an
inappropriate over-loading. ->direct_IO may need to had handle allocate
space for holes or other details that are not relevant for swap.

So this patch introduces a new address_space operation: ->swap_rw. In
this patch it is used for reads, and a subsequent patch will switch writes
to use it.

No filesystem yet supports ->swap_rw, but that is not a problem because
no filesystem actually works with filesystem-based swap.
Only two filesystems set SWP_FS_OPS:
- cifs sets the flag, but ->direct_IO always fails so swap cannot work.
- nfs sets the flag, but ->direct_IO calls generic_write_checks()
which has failed on swap files for several releases.

To ensure that a NULL ->swap_rw isn't called, ->activate_swap() for both
NFS and cifs are changed to fail if ->swap_rw is not set. This can be
removed if/when the function is added.

Future patches will restore swap-over-NFS functionality.

To submit an async read with ->swap_rw() we need to allocate a structure
to hold the kiocb and other details. swap_readpage() cannot handle
transient failure, so we create a mempool to provide the structures.

Link: https://lkml.kernel.org/r/164859778125.29473.13430559328221330589.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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mm: drop swap_dirty_folio

folios that are written to swap are owned by the MM subsystem - not any
filesystem.

When such a folio is passed to a filesystem to be written out to a
swap-file, the files

mm: drop swap_dirty_folio

folios that are written to swap are owned by the MM subsystem - not any
filesystem.

When such a folio is passed to a filesystem to be written out to a
swap-file, the filesystem handles the data, but the folio itself does not
belong to the filesystem. So calling the filesystem's ->dirty_folio()
address_space operation makes no sense. This is for folios in the given
address space, and a folio to be written to swap does not exist in the
given address space.

So drop swap_dirty_folio() which calls the address-space's
->dirty_folio(), and always use noop_dirty_folio(), which is appropriate
for folios being swapped out.

Link: https://lkml.kernel.org/r/164859778123.29473.6900942583784889976.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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mm: create new mm/swap.h header file

Patch series "MM changes to improve swap-over-NFS support".

Assorted improvements for swap-via-filesystem.

This is a resend of these patches, rebased on curren

mm: create new mm/swap.h header file

Patch series "MM changes to improve swap-over-NFS support".

Assorted improvements for swap-via-filesystem.

This is a resend of these patches, rebased on current HEAD. The only
substantial changes is that swap_dirty_folio has replaced
swap_set_page_dirty.

Currently swap-via-fs (SWP_FS_OPS) doesn't work for any filesystem. It
has previously worked for NFS but that broke a few releases back. This
series changes to use a new ->swap_rw rather than ->readpage and
->direct_IO. It also makes other improvements.

There is a companion series already in linux-next which fixes various
issues with NFS. Once both series land, a final patch is needed which
changes NFS over to use ->swap_rw.


This patch (of 10):

Many functions declared in include/linux/swap.h are only used within mm/

Create a new "mm/swap.h" and move some of these declarations there.
Remove the redundant 'extern' from the function declarations.

[akpm@linux-foundation.org: mm/memory-failure.c needs mm/swap.h]
Link: https://lkml.kernel.org/r/164859751830.29473.5309689752169286816.stgit@noble.brown
Link: https://lkml.kernel.org/r/164859778120.29473.11725907882296224053.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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mm: Convert swap_readpage to call read_folio instead of readpage

This commit is split out so it can be dropped when resolving
conflicts with Neil Brown's series to stop calling ->readpage in
the swa

mm: Convert swap_readpage to call read_folio instead of readpage

This commit is split out so it can be dropped when resolving
conflicts with Neil Brown's series to stop calling ->readpage in
the swap code.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

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Merge tag 'v5.18-rc5' into sched/core to pull in fixes & to resolve a conflict

- sched/core is on a pretty old -rc1 base - refresh it to include recent fixes.
- this also allows up to resolve a (t

Merge tag 'v5.18-rc5' into sched/core to pull in fixes & to resolve a conflict

- sched/core is on a pretty old -rc1 base - refresh it to include recent fixes.
- this also allows up to resolve a (trivial) .mailmap conflict

Conflicts:
.mailmap

Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge tag 'v5.18-rc4' into next

Merge master into next, to bring in commit 5f24d5a579d1 ("mm, hugetlb:
allow for "high" userspace addresses"), which is needed as a
prerequisite for the series conver

Merge tag 'v5.18-rc4' into next

Merge master into next, to bring in commit 5f24d5a579d1 ("mm, hugetlb:
allow for "high" userspace addresses"), which is needed as a
prerequisite for the series converting powerpc to the generic mmap
logic.

show more ...

Merge 5.18-rc5 into usb-next

We need the USB fixes in here, and this resolves a merge issue in
drivers/usb/dwc3/drd.c

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-

Merge 5.18-rc5 into usb-next

We need the USB fixes in here, and this resolves a merge issue in
drivers/usb/dwc3/drd.c

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge drm/drm-next into drm-misc-next

Christian needs a backmerge to avoid a merge conflict for amdgpu.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Backmerge tag 'v5.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into drm-next

Linux 5.18-rc5

There was a build fix for arm I wanted in drm-next, so backmerge rather then c

Backmerge tag 'v5.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into drm-next

Linux 5.18-rc5

There was a build fix for arm I wanted in drm-next, so backmerge rather then cherry-pick.

Signed-off-by: Dave Airlie <airlied@redhat.com>

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block: ignore RWF_HIPRI hint for sync dio

So far bio is marked as REQ_POLLED if RWF_HIPRI/IOCB_HIPRI is passed
from userspace sync io interface, then block layer tries to poll until
the bio is compl

block: ignore RWF_HIPRI hint for sync dio

So far bio is marked as REQ_POLLED if RWF_HIPRI/IOCB_HIPRI is passed
from userspace sync io interface, then block layer tries to poll until
the bio is completed. But the current implementation calls
blk_io_schedule() if bio_poll() returns 0, and this way causes io hang or
timeout easily.

But looks no one reports this kind of issue, which should have been
triggered in normal io poll sanity test or blktests block/007 as
observed by Changhui, that means it is very likely that no one uses it
or no one cares it.

Also after io_uring is invented, io poll for sync dio becomes legacy
interface.

So ignore RWF_HIPRI hint for sync dio.

CC: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Reported-by: Changhui Zhong <czhong@redhat.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Changhui Zhong <czhong@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220420143110.2679002-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

Merge 5.18-rc5 into tty-next

We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge 5.18-rc5 into driver-core-next

We need the kernfs/driver core fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge 5.18-rc5 into char-misc-next

We need the char-misc fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge tag 'v5.18-rc5' into devel

Merge in Linux 5.18-rc5 since new code to the STM32 driver
depend in a non-trivial way on the fixes merged in -rc5.

Signed-off-by: Linus Walleij <linus.walleij@lina

Merge tag 'v5.18-rc5' into devel

Merge in Linux 5.18-rc5 since new code to the STM32 driver
depend in a non-trivial way on the fixes merged in -rc5.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

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Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes, such as the llvm one for ubuntu:22.04.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

drivers/net/ethernet/microchip/lan966x/lan966x_main.c
d08ed852560e ("net: lan966x: Make sure to release ptp interrupt")
c8349639324

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

drivers/net/ethernet/microchip/lan966x/lan966x_main.c
d08ed852560e ("net: lan966x: Make sure to release ptp interrupt")
c8349639324a ("net: lan966x: Add FDMA functionality")

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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Merge branch 'topic/cs35l41' into for-next

Pull CS35L41 codec updates

Signed-off-by: Takashi Iwai <tiwai@suse.de>

Merge drm/drm-next into drm-intel-gt-next

Pull in TTM changes needed for DG2 CCS enabling from Ram.

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Merge drm/drm-next into drm-intel-next

Sync up with v5.18-rc1, in particular to get 5e3094cfd9fb
("drm/i915/xehpsdv: Add has_flat_ccs to device info").

Signed-off-by: Jani Nikula <jani.nikula@intel

Merge drm/drm-next into drm-intel-next

Sync up with v5.18-rc1, in particular to get 5e3094cfd9fb
("drm/i915/xehpsdv: Add has_flat_ccs to device info").

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

show more ...

Merge drm/drm-next into drm-misc-next

Let's start the 5.19 development cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge tag 'asoc-fix-v5.18-rc3' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v5.18

A collection of fixes that came in since the merge window, plus

Merge tag 'asoc-fix-v5.18-rc3' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v5.18

A collection of fixes that came in since the merge window, plus one new
device ID for an x86 laptop. Nothing that really stands out with
particularly big impact outside of the affected device.

show more ...

Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
"14 patches.

Subsystems affected by this patch series: MAINTAINERS, binfmt, and
mm (tmpfs, secretmem, kasan, kfen

Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
"14 patches.

Subsystems affected by this patch series: MAINTAINERS, binfmt, and
mm (tmpfs, secretmem, kasan, kfence, pagealloc, zram, compaction,
hugetlb, vmalloc, and kmemleak)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm: kmemleak: take a full lowmem check in kmemleak_*_phys()
mm/vmalloc: fix spinning drain_vmap_work after reading from /proc/vmcore
revert "fs/binfmt_elf: use PT_LOAD p_align values for static PIE"
revert "fs/binfmt_elf: fix PT_LOAD p_align values for loaders"
hugetlb: do not demote poisoned hugetlb pages
mm: compaction: fix compiler warning when CONFIG_COMPACTION=n
mm: fix unexpected zeroed page mapping with zram swap
mm, page_alloc: fix build_zonerefs_node()
mm, kfence: support kmem_dump_obj() for KFENCE objects
kasan: fix hw tags enablement when KUNIT tests are disabled
irq_work: use kasan_record_aux_stack_noalloc() record callstack
mm/secretmem: fix panic when growing a memfd_secret
tmpfs: fix regressions from wider use of ZERO_PAGE
MAINTAINERS: Broadcom internal lists aren't maintainers

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mm: fix unexpected zeroed page mapping with zram swap

Two processes under CLONE_VM cloning, user process can be corrupted by
seeing zeroed page unexpectedly.

CPU A CPU

mm: fix unexpected zeroed page mapping with zram swap

Two processes under CLONE_VM cloning, user process can be corrupted by
seeing zeroed page unexpectedly.

CPU A CPU B

do_swap_page do_swap_page
SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path
swap_readpage valid data
swap_slot_free_notify
delete zram entry
swap_readpage zeroed(invalid) data
pte_lock
map the *zero data* to userspace
pte_unlock
pte_lock
if (!pte_same)
goto out_nomap;
pte_unlock
return and next refault will
read zeroed data

The swap_slot_free_notify is bogus for CLONE_VM case since it doesn't
increase the refcount of swap slot at copy_mm so it couldn't catch up
whether it's safe or not to discard data from backing device. In the
case, only the lock it could rely on to synchronize swap slot freeing is
page table lock. Thus, this patch gets rid of the swap_slot_free_notify
function. With this patch, CPU A will see correct data.

CPU A CPU B

do_swap_page do_swap_page
SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path
swap_readpage original data
pte_lock
map the original data
swap_free
swap_range_free
bd_disk->fops->swap_slot_free_notify
swap_readpage read zeroed data
pte_unlock
pte_lock
if (!pte_same)
goto out_nomap;
pte_unlock
return
on next refault will see mapped data by CPU B

The concern of the patch would increase memory consumption since it
could keep wasted memory with compressed form in zram as well as
uncompressed form in address space. However, most of cases of zram uses
no readahead and do_swap_page is followed by swap_free so it will free
the compressed form from in zram quickly.

Link: https://lkml.kernel.org/r/YjTVVxIAsnKAXjTd@google.com
Fixes: 0bcac06f27d7 ("mm, swap: skip swapcache for swapin of synchronous device")
Reported-by: Ivan Babrou <ivan@cloudflare.com>
Tested-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org> [4.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

Merge drm/drm-fixes into drm-misc-fixes

Let's start the 5.18 fixes cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge branches 'fixes' and 'misc' into for-linus