linux_dsm_epyc7002/drivers/misc
Michal Hocko 0ee931c4e3 mm: treewide: remove GFP_TEMPORARY allocation flag
GFP_TEMPORARY was introduced by commit e12ba74d8f ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE.  It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation.  As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag.  How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory.  So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification.  I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring.  This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse.  Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL.  Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic.  It
seems to be a heuristic without any measured advantage for most (if not
all) its current users.  The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers.  So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
  Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-13 18:53:16 -07:00
..
altera-stapl drivers/misc/altera-stapl/altera.c: remove extraneous KERN_INFO prefix 2015-06-25 17:00:38 -07:00
c2port drivers/misc/c2port/c2port-duramar2150.c: checking for NULL instead of IS_ERR() 2017-05-08 17:15:10 -07:00
cb710 mmc: cb710: drop free_irq for devm_request_irq allocated irq 2013-09-26 13:55:30 -07:00
cxl mm: treewide: remove GFP_TEMPORARY allocation flag 2017-09-13 18:53:16 -07:00
echo staging: echo: move to drivers/misc/ 2014-02-28 14:08:42 -08:00
eeprom eeprom: idt_89hpesx: Support both ACPI and OF probing 2017-08-31 18:49:41 +02:00
genwqe sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
ibmasm sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
lis3lv02d misc: lis3lv02d: constify attribute_group structures. 2017-08-28 16:55:48 +02:00
mei mei: make device_type const 2017-08-28 11:59:39 +02:00
mic misc/mic/scif: update to new mmu_notifier semantic 2017-08-31 16:13:00 -07:00
sgi-gru sgi-gru: update to new mmu_notifier semantic 2017-08-31 16:13:00 -07:00
sgi-xp sgi-xp: Use designated initializers 2017-05-28 10:22:42 -07:00
ti-st misc: ti-st: constify attribute_group structures. 2017-08-28 16:55:48 +02:00
vmw_vmci vmci: fix duplicated code for different branches 2017-08-28 16:55:50 +02:00
ad525x_dpot-i2c.c misc: ad525x_dpot: Remove unnecessary MODULE_ALIAS() 2015-09-20 19:33:29 -07:00
ad525x_dpot-spi.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
ad525x_dpot.c misc: ad525x_dpot: Fix the enabling of the "otpXen" attributes 2016-03-01 16:55:13 -08:00
ad525x_dpot.h
apds990x.c misc: apds990x: constify attribute_group structures. 2017-08-28 16:55:49 +02:00
apds9802als.c misc: apds9802als: constify i2c_device_id 2017-08-28 16:55:49 +02:00
aspeed-lpc-ctrl.c drivers/misc: aspeed-lpc-ctrl: fix printk format warning again 2017-04-08 17:37:20 +02:00
aspeed-lpc-snoop.c drivers/misc: (aspeed-lpc-snoop): Add ast2400 to compat 2017-07-17 17:23:16 +02:00
atmel_tclib.c misc: atmel_tclib: get and use slow clock 2015-10-06 12:33:14 +02:00
atmel-ssc.c misc: atmel-ssc: register as sound DAI if #sound-dai-cells is present 2016-12-15 12:13:31 +00:00
bh1770glc.c misc: bh1770glc: constify attribute_group structures. 2017-08-28 16:55:48 +02:00
cs5535-mfgpt.c misc: drop owner assignment from platform_drivers 2014-10-20 16:20:54 +02:00
ds1682.c MISC: add const to bin_attribute structures 2017-08-28 16:55:48 +02:00
dummy-irq.c Annotate hardware config module parameters in drivers/misc/ 2017-04-20 12:02:32 +01:00
enclosure.c scsi: ses: do not add a device to an enclosure if enclosure_add_links() fails. 2017-07-01 16:52:38 -04:00
fsa9480.c treewide: fix comments and printk msgs 2014-01-07 15:06:07 +01:00
hmc6352.c misc: hmc6352: constify i2c_device_id 2017-08-28 16:55:49 +02:00
hpilo.c misc: hpilo: constify pci_device_id. 2017-08-28 16:55:48 +02:00
hpilo.h misc: hpilo: increase number of max supported channels 2012-06-14 17:22:12 -07:00
ics932s401.c hwmon: Change my email address. 2013-08-27 08:28:01 -07:00
ioc4.c misc: ioc4: constify pci_device_id. 2017-08-28 16:55:48 +02:00
isl29003.c misc: Drop owner assignment from i2c_driver 2015-08-10 08:37:35 +02:00
isl29020.c misc: isl29020: constify i2c_device_id 2017-08-28 16:55:49 +02:00
Kconfig drivers/misc: add Aspeed LPC snoop driver 2017-06-03 19:15:18 +09:00
kgdbts.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
lattice-ecp3-config.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
lkdtm_bugs.c lkdtm: Add -fstack-protector-strong test 2017-08-15 12:27:35 -07:00
lkdtm_core.c lkdtm: Add -fstack-protector-strong test 2017-08-15 12:27:35 -07:00
lkdtm_heap.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
lkdtm_perms.c lkdtm: Do not use flush_icache_range() on user addresses 2016-11-10 15:34:56 +01:00
lkdtm_refcount.c lkdtm: fix spelling mistake: "incremeted" -> "incremented" 2017-08-28 17:47:11 +02:00
lkdtm_rodata.c lkdtm: Mark lkdtm_rodata_do_nothing() notrace 2016-08-31 13:12:38 +02:00
lkdtm_usercopy.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
lkdtm.h lkdtm: Add -fstack-protector-strong test 2017-08-15 12:27:35 -07:00
Makefile lkdtm: Provide more complete coverage for REFCOUNT tests 2017-07-26 14:38:03 -07:00
pch_phub.c MISC: add const to bin_attribute structures 2017-08-28 16:55:48 +02:00
pci_endpoint_test.c misc: pci_endpoint_test: Enable/Disable MSI using module param 2017-08-29 16:00:40 -05:00
phantom.c misc: phantom: remove deprecated IRQF_DISABLED 2013-10-16 12:36:10 -07:00
pti.c misc: pti: remove unnecessary pci_set_drvdata() 2013-09-26 09:13:54 -07:00
qcom-coincell.c ARM: qcom: silence an uninitialized variable warning 2016-05-01 14:20:04 -07:00
spear13xx_pcie_gadget.c spear13xx_pcie_gadget: use per-attribute show and store methods 2015-10-13 22:17:40 -07:00
sram-exec.c misc: sram-exec: Use aligned fncpy instead of memcpy 2017-05-18 17:37:52 +02:00
sram.c misc: Convert to using %pOF instead of full_name 2017-08-28 16:55:49 +02:00
sram.h misc: sram: Integrate protect-exec reserved sram area type 2017-01-25 11:48:03 +01:00
ti_dac7512.c spi: Drop owner assignment from spi_drivers 2015-10-28 10:30:17 +09:00
tifm_7xx1.c misc: tifm: constify pci_device_id. 2017-08-28 16:55:48 +02:00
tifm_core.c tifm: convert bus code to use dev_groups 2013-10-16 18:40:58 -07:00
tsl2550.c misc: tsl2550: Add OF device ID table 2017-04-08 18:22:59 +02:00
vexpress-syscfg.c sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
vmw_balloon.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00