14 Jan, 2009
2 commits
-
Impact: cleanup
Change the protection parameter for track_pfn_vma_new() into a pgprot_t pointer.
Subsequent patch changes the x86 PAT handling to return a compatible
memtype in pgprot_t, if what was requested cannot be allowed due to conflicts.
No fuctionality change in this patch.Signed-off-by: Venkatesh Pallipadi
Signed-off-by: Suresh Siddha
Signed-off-by: Ingo Molnar -
Impact: fix (harmless) double-free of memtype entries and avoid warning
On track_pfn_vma_new() failure, reset the vm_flags so that there will be
no second cleanup happening when upper level routines call unmap_vmas().This patch fixes part of the bug reported here:
http://marc.info/?l=linux-kernel&m=123108883716357&w=2
Specifically the error message:
X:5010 freeing invalid memtype d0000000-d0101000
Is due to multiple frees on error path, will not happen with the patch below.
Signed-off-by: Venkatesh Pallipadi
Signed-off-by: Suresh Siddha
Signed-off-by: Ingo Molnar
12 Jan, 2009
1 commit
-
Some code (nfs/sunrpc) uses socket ops on kernel memory while holding
the mmap_sem, this is safe because kernel memory doesn't get paged out,
therefore we'll never actually fault, and the might_fault() annotations
will generate false positives.Reported-by: "J. Bruce Fields"
Signed-off-by: Peter Zijlstra
Signed-off-by: Ingo Molnar
10 Jan, 2009
1 commit
-
* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-nommu:
NOMMU: Support XIP on initramfs
NOMMU: Teach kobjsize() about VMA regions.
FLAT: Don't attempt to expand the userspace stack to fill the space allocated
FDPIC: Don't attempt to expand the userspace stack to fill the space allocated
NOMMU: Improve procfs output using per-MM VMAs
NOMMU: Make mmap allocation page trimming behaviour configurable.
NOMMU: Make VMAs per MM as for MMU-mode linux
NOMMU: Delete askedalloc and realalloc variables
NOMMU: Rename ARM's struct vm_region
NOMMU: Fix cleanup handling in ramfs_nommu_get_umapped_area()
09 Jan, 2009
36 commits
-
Update the memory controller to use its hierarchy_mutex rather than
calling cgroup_lock() to protected against cgroup_mkdir()/cgroup_rmdir()
from occurring in its hierarchy.Signed-off-by: Paul Menage
Tested-by: KAMEZAWA Hiroyuki
Cc: Li Zefan
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, you can see following even when swap accounting is enabled.
1. Create Group 01, and 02.
2. allocate a "file" on tmpfs by a task under 01.
3. swap out the "file" (by memory pressure)
4. Read "file" from a task in group 02.
5. the charge of "file" is moved to group 02.This is not ideal behavior. This is because SwapCache which was loaded
by read-ahead is not taken into account..This is a patch to fix shmem's swapcache behavior.
- remove mem_cgroup_cache_charge_swapin().
- Add SwapCache handler routine to mem_cgroup_cache_charge().
By this, shmem's file cache is charged at add_to_page_cache()
with GFP_NOWAIT.
- pass the page of swapcache to shrink_mem_cgroup.Signed-off-by: KAMEZAWA Hiroyuki
Cc: Daisuke Nishimura
Cc: Balbir Singh
Cc: Paul Menage
Cc: Li Zefan
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, a page can be deleted from SwapCache while do_swap_page().
memcg-fix-swap-accounting-leak-v3.patch handles that, but, LRU handling is
still broken. (above behavior broke assumption of memcg-synchronized-lru
patch.)This patch is a fix for LRU handling (especially for per-zone counters).
At charging SwapCache,
- Remove page_cgroup from LRU if it's not used.
- Add page cgroup to LRU if it's not linked to.Reported-by: Daisuke Nishimura
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Paul Menage
Cc: Li Zefan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
From:KAMEZAWA Hiroyuki
css_tryget() newly is added and we can know css is alive or not and get
refcnt of css in very safe way. ("alive" here means "rmdir/destroy" is
not called.)This patch replaces css_get() to css_tryget(), where I cannot explain
why css_get() is safe. And removes memcg->obsolete flag.Reviewed-by: Daisuke Nishimura
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Paul Menage
Cc: Daisuke Nishimura
Cc: Li Zefan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
1. Fix double-free BUG in error route of mem_cgroup_create().
mem_cgroup_free() itself frees per-zone-info.
2. Making refcnt of memcg simple.
Add 1 refcnt at creation and call free when refcnt goes down to 0.Reviewed-by: Daisuke Nishimura
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Paul Menage
Cc: Daisuke Nishimura
Cc: Li Zefan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix swapin charge operation of memcg.
Now, memcg has hooks to swap-out operation and checks SwapCache is really
unused or not. That check depends on contents of struct page. I.e. If
PageAnon(page) && page_mapped(page), the page is recoginized as
still-in-use.Now, reuse_swap_page() calles delete_from_swap_cache() before establishment
of any rmap. Then, in followinig sequence(Page fault with WRITE)
try_charge() (charge += PAGESIZE)
commit_charge() (Check page_cgroup is used or not..)
reuse_swap_page()
-> delete_from_swapcache()
-> mem_cgroup_uncharge_swapcache() (charge -= PAGESIZE)
......
New charge is uncharged soon....
To avoid this, move commit_charge() after page_mapcount() goes up to 1.
By this,try_charge() (usage += PAGESIZE)
reuse_swap_page() (may usage -= PAGESIZE if PCG_USED is set)
commit_charge() (If page_cgroup is not marked as PCG_USED,
add new charge.)
Accounting will be correct.Changelog (v2) -> (v3)
- fixed invalid charge to swp_entry==0.
- updated documentation.
Changelog (v1) -> (v2)
- fixed comment.[nishimura@mxp.nes.nec.co.jp: swap accounting leak doc fix]
Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Tested-by: Balbir Singh
Cc: Hugh Dickins
Cc: Daisuke Nishimura
Signed-off-by: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mem_cgroup_hierarchicl_reclaim() works properly even when !use_hierarchy
now (by memcg-hierarchy-avoid-unnecessary-reclaim.patch), so, instead of
try_to_free_mem_cgroup_pages(), it should be used in many cases.The only exception is force_empty. The group has no children in this
case.Signed-off-by: Daisuke Nishimura
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mpol_rebind_mm(), which can be called from cpuset_attach(), does
down_write(mm->mmap_sem). This means down_write(mm->mmap_sem) can be
called under cgroup_mutex.OTOH, page fault path does down_read(mm->mmap_sem) and calls
mem_cgroup_try_charge_xxx(), which may eventually calls
mem_cgroup_out_of_memory(). And mem_cgroup_out_of_memory() calls
cgroup_lock(). This means cgroup_lock() can be called under
down_read(mm->mmap_sem).If those two paths race, deadlock can happen.
This patch avoid this deadlock by:
- remove cgroup_lock() from mem_cgroup_out_of_memory().
- define new mutex (memcg_tasklist) and serialize mem_cgroup_move_task()
(->attach handler of memory cgroup) and mem_cgroup_out_of_memory.Signed-off-by: Daisuke Nishimura
Reviewed-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
After previous patch, mem_cgroup_try_charge is not used by anyone, so we
can remove it.Signed-off-by: Daisuke Nishimura
Acked-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I think triggering OOM at mem_cgroup_prepare_migration would be just a bit
overkill. Returning -ENOMEM would be enough for
mem_cgroup_prepare_migration. The caller would handle the case anyway.Signed-off-by: Daisuke Nishimura
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Show "real" limit of memcg. This helps my debugging and maybe useful for
users.While testing hierarchy like this
mount -t cgroup none /cgroup -t memory
mkdir /cgroup/A
set use_hierarchy==1 to "A"
mkdir /cgroup/A/01
mkdir /cgroup/A/01/02
mkdir /cgroup/A/01/03
mkdir /cgroup/A/01/03/04
mkdir /cgroup/A/08
mkdir /cgroup/A/08/01
....
and set each own limit to them, "real" limit of each memcg is unclear.
This patch shows real limit by checking all ancestors.Changelog: (v1) -> (v2)
- remove "if" and use "min(a,b)"Acked-by: Balbir Singh
Signed-off-by: KAMEZAWA Hiroyuki
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, inactive_ratio of memcg is calculated at setting limit.
because page_alloc.c does so and current implementation is straightforward
porting.However, memcg introduced hierarchy feature recently. In hierarchy
restriction, memory limit is not only decided memory.limit_in_bytes of
current cgroup, but also parent limit and sibling memory usage.Then, The optimal inactive_ratio is changed frequently. So, everytime
calculation is better.Tested-by: KAMEZAWA Hiroyuki
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, /proc/sys/vm/swappiness can change swappiness ratio for global
reclaim. However, memcg reclaim doesn't have tuning parameter for itself.In general, the optimal swappiness depend on workload. (e.g. hpc
workload need to low swappiness than the others.)Then, per cgroup swappiness improve administrator tunability.
Signed-off-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, mem_cgroup doesn't have own lock and almost its member doesn't
need. (e.g. mem_cgroup->info is protected by zone lock, mem_cgroup->stat
is per cpu variable)However, there is one explict exception. mem_cgroup->prev_priorit need
lock, but doesn't protect. Luckly, this is NOT bug because prev_priority
isn't used for current reclaim code.However, we plan to use prev_priority future again. Therefore, fixing is
better.In addition, we plan to reuse this lock for another member. Then
"reclaim_param_lock" name is better than "prev_priority_lock".Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Rename scan_global_lru() to scanning_global_lru().
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add the following four fields to memory.stat file:
- inactive_ratio
- recent_rotated_anon
- recent_rotated_file
- recent_scanned_anon
- recent_scanned_fileAcked-by: Rik van Riel
Signed-off-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, get_scan_ratio() return correct value although memcg reclaim. Then,
mem_cgroup_calc_reclaim() can be removed.So, memcg reclaim get the same capability of anon/file reclaim balancing
as global reclaim now.Acked-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Introduce mem_cgroup_per_zone::reclaim_stat member and its statics
collecting function.Now, get_scan_ratio() can calculate correct value on memcg reclaim.
[hugh@veritas.com: avoid reclaim_stat oops when disabled]
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Introduce mem_cgroup_zone_nr_pages(). It is called by zone_nr_pages()
helper function.This patch doesn't have any behavior change.
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Acked-by: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The inactive_anon_is_low() is key component of active/inactive anon
balancing on reclaim. However current inactive_anon_is_low() function
only consider global reclaim.Therefore, we need following ugly scan_global_lru() condition.
if (lru == LRU_ACTIVE_ANON &&
(!scan_global_lru(sc) || inactive_anon_is_low(zone))) {
shrink_active_list(nr_to_scan, zone, sc, priority, file);
return 0;it cause that memcg reclaim always deactivate pages when shrink_list() is
called. To make mem_cgroup_inactive_anon_is_low() improve active/inactive
anon balancing of memcgroup.Acked-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Cyrill Gorcunov
Cc: "Pekka Enberg"
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
If CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y, page_cgroup::mem_cgroup can be NULL.
Therefore null checking is better.A later patch uses this function.
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, get_scan_ratio() always calculate the balancing value for
global reclaim and memcg reclaim doesn't use it. Therefore it doesn't
have scan_global_lru() condition.However, we plan to expand get_scan_ratio() to be usable for memcg too,
latter. Then, The dependency code of global reclaim in the
get_scan_ratio() insert into scan_global_lru() condision explictly.This patch doesn't have any functional change.
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add zone_nr_pages() helper function.
It is used by a later patch. This patch doesn't have any functional
change.Reviewed-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Acked-by: Rik van Riel
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add zone_reclam_stat struct for later enhancement.
A later patch uses this. This patch doesn't any behavior change (yet).
Reviewed-by: KAMEZAWA Hiroyuki
Signed-off-by: KOSAKI Motohiro
Acked-by: Rik van Riel
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The inactive_anon_is_low() is called only vmscan. Then it can move to
vmscan.cThis patch doesn't have any functional change.
Reviewd-by: KAMEZAWA Hiroyuki
Acked-by: Rik van Riel
Signed-off-by: KOSAKI Motohiro
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
If hierarchy is not used, no tree-walk is necessary.
Reviewed-by: KOSAKI Motohiro
Signed-off-by: Daisuke Nishimura
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
css's refcnt is dropped before end of following access.
Hold it until end of access.Reported-by: Li Zefan
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There are scatterd calls of res_counter_check_under_limit(), and most of
them don't take mem+swap accounting into account.define mem_cgroup_check_under_limit() and avoid direct use of
res_counter_check_limit().Reported-by: Daisuke Nishimura
Signed-off-by: Daisuke Nishimura
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove unnecessary codes (...fragments of not-implemented
functionalilty...)Reported-by: Nikanth Karthikesan
Signed-off-by: Nikanth Karthikesan
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
My patch, memcg-fix-gfp_mask-of-callers-of-charge.patch changed gfp_mask
of callers of charge to be GFP_HIGHUSER_MOVABLE for showing what will
happen at memory reclaim.But in recent discussion, it's NACKed because it sounds ugly.
This patch is for reverting it and add some clean up to gfp_mask of
callers of charge. No behavior change but need review before generating
HUNK in deep queue.This patch also adds explanation to meaning of gfp_mask passed to charge
functions in memcontrol.h.Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
check_under_limit logic was wrong and this check should be against
mem_over_limit rather than mem.Reported-by: Li Zefan
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Badari Pulavarty
Cc: Jan Blunck
Cc: Hirokazu Takahashi
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Current mmtom has new oom function as pagefault_out_of_memory(). It's
added for select bad process rathar than killing current.When memcg hit limit and calls OOM at page_fault, this handler called and
system-wide-oom handling happens. (means kernel panics if panic_on_oom is
true....)To avoid overkill, check memcg's recent behavior before starting
system-wide-oom.And this patch also fixes to guarantee "don't accnout against process with
TIF_MEMDIE". This is necessary for smooth OOM.[akpm@linux-foundation.org: build fix]
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Li Zefan
Cc: Balbir Singh
Cc: Daisuke Nishimura
Cc: Badari Pulavarty
Cc: Jan Blunck
Cc: Hirokazu Takahashi
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Don't enable multiple hierarchy support by default. This patch introduces
a features element that can be set to enable the nested depth hierarchy
feature. This feature can only be enabled when the cgroup for which the
feature this is enabled, has no children.Signed-off-by: Balbir Singh
Cc: YAMAMOTO Takashi
Cc: Paul Menage
Cc: Li Zefan
Cc: David Rientjes
Cc: Pavel Emelianov
Cc: Dhaval Giani
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch introduces hierarchical reclaim. When an ancestor goes over
its limit, the charging routine points to the parent that is above its
limit. The reclaim process then starts from the last scanned child of the
ancestor and reclaims until the ancestor goes below its limit.[akpm@linux-foundation.org: coding-style fixes]
[d-nishimura@mtf.biglobe.ne.jp: mem_cgroup_from_res_counter should handle both mem->res and mem->memsw]
Signed-off-by: Balbir Singh
Cc: YAMAMOTO Takashi
Cc: Paul Menage
Cc: Li Zefan
Cc: David Rientjes
Cc: Pavel Emelianov
Cc: Dhaval Giani
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add support for building hierarchies in resource counters. Cgroups allows
us to build a deep hierarchy, but we currently don't link the resource
counters belonging to the memory controller control groups, in the same
fashion as the corresponding cgroup entries in the cgroup hierarchy. This
patch provides the infrastructure for resource counters that have the same
hiearchy as their cgroup counter parts.These set of patches are based on the resource counter hiearchy patches
posted by Pavel Emelianov.NOTE: Building hiearchies is expensive, deeper hierarchies imply charging
the all the way up to the root. It is known that hiearchies are
expensive, so the user needs to be careful and aware of the trade-offs
before creating very deep ones.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Balbir Singh
Cc: YAMAMOTO Takashi
Cc: Paul Menage
Cc: Li Zefan
Cc: David Rientjes
Cc: Pavel Emelianov
Cc: Dhaval Giani
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We check mem_cgroup is disabled or not by checking
mem_cgroup_subsys.disabled. I think it has more references than expected,
now.replacing
if (mem_cgroup_subsys.disabled)
with
if (mem_cgroup_disabled())give us good look, I think.
[kamezawa.hiroyu@jp.fujitsu.com: fix typo]
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Li Zefan
Cc: Balbir Singh
Cc: Pavel Emelyanov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
