WSL2-Linux-Kernel/drivers/block
Michal Hocko 32d6bd9059 tree wide: get rid of __GFP_REPEAT for order-0 allocations part I
This is the third version of the patchset previously sent [1].  I have
basically only rebased it on top of 4.7-rc1 tree and dropped "dm: get
rid of superfluous gfp flags" which went through dm tree.  I am sending
it now because it is tree wide and chances for conflicts are reduced
considerably when we want to target rc2.  I plan to send the next step
and rename the flag and move to a better semantic later during this
release cycle so we will have a new semantic ready for 4.8 merge window
hopefully.

Motivation:

While working on something unrelated I've checked the current usage of
__GFP_REPEAT in the tree.  It seems that a majority of the usage is and
always has been bogus because __GFP_REPEAT has always been about costly
high order allocations while we are using it for order-0 or very small
orders very often.  It seems that a big pile of them is just a
copy&paste when a code has been adopted from one arch to another.

I think it makes some sense to get rid of them because they are just
making the semantic more unclear.  Please note that GFP_REPEAT is
documented as

* __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt

* _might_ fail.  This depends upon the particular VM implementation.
  while !costly requests have basically nofail semantic.  So one could
  reasonably expect that order-0 request with __GFP_REPEAT will not loop
  for ever.  This is not implemented right now though.

I would like to move on with __GFP_REPEAT and define a better semantic
for it.

  $ git grep __GFP_REPEAT origin/master | wc -l
  111
  $ git grep __GFP_REPEAT | wc -l
  36

So we are down to the third after this patch series.  The remaining
places really seem to be relying on __GFP_REPEAT due to large allocation
requests.  This still needs some double checking which I will do later
after all the simple ones are sorted out.

I am touching a lot of arch specific code here and I hope I got it right
but as a matter of fact I even didn't compile test for some archs as I
do not have cross compiler for them.  Patches should be quite trivial to
review for stupid compile mistakes though.  The tricky parts are usually
hidden by macro definitions and thats where I would appreciate help from
arch maintainers.

[1] http://lkml.kernel.org/r/1461849846-27209-1-git-send-email-mhocko@kernel.org

This patch (of 19):

__GFP_REPEAT has a rather weak semantic but since it has been introduced
around 2.6.12 it has been ignored for low order allocations.  Yet we
have the full kernel tree with its usage for apparently order-0
allocations.  This is really confusing because __GFP_REPEAT is
explicitly documented to allow allocation failures which is a weaker
semantic than the current order-0 has (basically nofail).

Let's simply drop __GFP_REPEAT from those places.  This would allow to
identify place which really need allocator to retry harder and formulate
a more specific semantic for what the flag is supposed to do actually.

Link: http://lkml.kernel.org/r/1464599699-30131-2-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com> [for tile]
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: John Crispin <blogic@openwrt.org>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24 17:23:52 -07:00
..
aoe tree wide: get rid of __GFP_REPEAT for order-0 allocations part I 2016-06-24 17:23:52 -07:00
drbd Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-05-17 16:26:30 -07:00
mtip32xx mtip32xx: remove call to blk_queue_flush() 2016-04-12 16:00:39 -06:00
paride paride: make 'verbose' parameter an 'int' again 2016-03-15 16:55:16 -07:00
rsxx rsxx: don't open-code memdup_user() 2016-01-06 08:25:24 -05:00
xen-blkback block: kill off q->flush_flags 2016-04-13 13:33:19 -06:00
zram zram: introduce per-device debug_stat sysfs node 2016-05-20 17:58:30 -07:00
DAC960.c block: use pci_zalloc_consistent 2014-08-08 15:57:28 -07:00
DAC960.h Fix DAC960 driver on machines which don't support 64-bit DMA 2007-09-11 17:21:19 -07:00
Kconfig cpqarray: remove it from the kernel 2016-03-14 09:06:01 -06:00
Makefile drivers:block: cpqarray clean up 2016-03-15 15:59:47 -07:00
amiflop.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
ataflop.c Merge branch 'for-3.16/core' of git://git.kernel.dk/linux-block into next 2014-06-02 09:29:34 -07:00
brd.c dax: enable dax in the presence of known media errors (badblocks) 2016-05-18 12:16:56 -06:00
cciss.c SCSI misc on 20160113 2016-01-13 19:37:36 -08:00
cciss.h cciss: Adds simple mode functionality 2011-08-08 11:40:15 +02:00
cciss_cmd.h cciss: use new doorbell-bit-5 reset method 2011-05-06 08:23:55 -06:00
cciss_scsi.c scsi: Do not set cmd_per_lun to 1 in the host template 2015-05-31 18:06:28 -07:00
cciss_scsi.h cciss: add cciss_tape_cmds module paramter 2011-05-06 08:23:59 -06:00
cryptoloop.c block: cryptoloop - Use new skcipher interface 2016-01-27 20:35:43 +08:00
floppy.c floppy: refactor open() flags handling 2016-02-06 23:00:22 +01:00
hd.c block: hd: remove deprecated IRQF_DISABLED 2014-10-01 08:16:07 -06:00
loop.c Merge branch 'for-4.7/drivers' of git://git.kernel.dk/linux-block 2016-05-17 16:03:32 -07:00
loop.h block: loop: support DIO & AIO 2015-09-23 11:01:16 -06:00
mg_disk.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
nbd.c nbd: pass the nbd pointer for flags debugfs 2016-06-08 09:03:54 -06:00
null_blk.c null_blk: add lightnvm null_blk device to the nullb_list 2016-03-18 18:10:37 -07:00
osdblk.c osdblk: switch to using blk_queue_write_cache() 2016-04-12 16:00:39 -06:00
pktcdvd.c Merge branch 'for-4.4/io-poll' of git://git.kernel.dk/linux-block 2015-11-10 17:23:49 -08:00
ps3disk.c ps3disk: switch to using blk_queue_write_cache() 2016-04-12 16:00:39 -06:00
ps3vram.c block: change ->make_request_fn() and users to return a queue cookie 2015-11-07 10:40:46 -07:00
rbd.c libceph: replace ceph_monc_request_next_osdmap() 2016-05-26 01:15:30 +02:00
rbd_types.h rbd: get rid of RBD_MAX_SEG_NAME_LEN 2012-12-17 08:37:29 -06:00
skd_main.c skd: remove broken discard support 2016-04-25 19:12:38 -06:00
skd_s1120.h skd: fix formatting in skd_s1120.h 2013-11-08 09:10:30 -07:00
smart1,2.h fix typos 'comamnd' -> 'command' in comments 2011-02-02 11:31:21 +01:00
sunvdc.c sunvdc: reconnect ldc after vds service domain restarts 2014-12-11 18:52:45 -08:00
swim.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
swim3.c powerpc: Move Power Macintosh drivers to generic byteswappers 2015-03-23 14:29:40 +11:00
swim_asm.S m68k: mac - Add SWIM floppy support 2009-03-26 21:15:27 +01:00
sx8.c sx8: use real time for the command seconds 2015-12-23 08:42:59 -07:00
umem.c block: change ->make_request_fn() and users to return a queue cookie 2015-11-07 10:40:46 -07:00
umem.h drivers/block/umem: trim trailing whitespace 2007-10-10 09:25:59 +02:00
virtio_blk.c virtio_blk: switch to using blk_queue_write_cache() 2016-04-12 16:00:39 -06:00
xen-blkfront.c xen-blkfront: fix resume issues after a migration 2016-06-08 13:54:46 -04:00
xsysace.c block: systemace: Remove .owner field for driver 2014-08-21 20:37:54 -05:00
z2ram.c block: remove struct request buffer member 2014-04-15 14:03:02 -06:00