Thanks Robin for Review.
Please find reply in-lined.
On Tue, May 5, 2020 at 10:07 PM Robin Murphy wrote:
>
> [ fixed Will's address... ]
>
> On 2020-05-05 4:59 pm, Prabhakar Kushwaha wrote:
> > An SMMU Stream table is created by the primary kernel. This table is
> > used by the SMMU to perform a
> On May 6, 2020, at 6:28 PM, Rafael Aquini wrote:
>
> Analogously to the introduction of panic_on_warn, this patch
> introduces a kernel option named panic_on_taint in order to
> provide a simple and generic way to stop execution and catch
> a coredump when the kernel gets tainted by any give
To support deferred initialization of page structs for preserved pages,
separate memblocks containing preserved pages by setting a new flag
when adding them to the memblock reserved list.
Signed-off-by: Anthony Yznaga
---
include/linux/memblock.h | 7 +++
mm/memblock.c| 8 +++
Considerable contention on the LRU lock happens when multiple threads
are used to insert pages into a shmem file in parallel. To alleviate this
provide a way for pages to be added to the same LRU to be staged so that
they can be added by splicing lists and updating stats once with the lock
held. Fo
Contention on the xarray lock when multiple threads are adding to the
same xarray can be mitigated by providing a way to add entries in
bulk.
Allow a caller to allocate and populate an xarray node outside of
the target xarray and then only take the xarray lock long enough to
import the node into i
When a kernel is loaded for kexec the address ranges where the kexec
segments will be copied to may conflict with pages already set to be
preserved. Provide a way to determine if preserved pages exist in a
specified range.
Signed-off-by: Anthony Yznaga
---
include/linux/pkram.h | 2 ++
mm/pkram
Reduce LRU lock contention when inserting shmem pages by staging pages
to be added to the same LRU and adding them en masse.
Signed-off-by: Anthony Yznaga
---
mm/shmem.c | 8 +++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index ca5edf580f24..678a396
Not all memory ranges can be used for saving preserved over-kexec data.
For example, a kexec kernel may be loaded before pages are preserved.
The memory regions where the kexec segments will be copied to on kexec
must not contain preserved pages or else they will be clobbered.
Originally-by: Vladi
Provide a way for a caller external to numa to ensure memblocks in the
memblock reserved list do not cross node boundaries and have a node id
assigned to them. This will be used by PKRAM to ensure initialization of
page structs for preserved pages can be deferred and multithreaded
efficiently.
Si
Improve performance by multithreading the work to preserve and restore
shmem pages.
Add 'pkram_max_threads=' kernel option to specify the maximum number
of threads to use to preserve or restore the pages of a shmem file.
The default is 16.
When preserving pages each thread saves chunks of a file
If shmem_insert_page() is called to insert a page that was preserved
using PKRAM on the current boot (i.e. preserved page is restored without
an intervening kexec boot), the page will still be charged to a memory
cgroup because it is never freed. Don't try to charge it again.
Signed-off-by: Anthon
This patch illustrates how the PKRAM API can be used for preserving tmpfs.
Two options are added to tmpfs:
The 'pkram=' option specifies the PKRAM node to load/save the
filesystem tree from/to.
The 'preserve' option initiates preservation of a read-only
filesystem tree.
If the 'pkr
To take advantage of optimizations when adding pages to the page cache
via shmem_insert_pages(), improve the likelihood that the pages array
passed to shmem_insert_pages() starts on an aligned index. Do this
when preserving pages by starting a new pkram_link page when the current
page is aligned a
shmem_insert_pages() currently loops over the array of pages passed
to it and calls shmem_add_to_page_cache() for each one. Prepare
for adding pages to the pagecache in bulk by adding and using a
shmem_add_pages_to_cache() call. For now it just iterates over
an array and adds pages individually, b
Keep preserved pages from being recycled during boot by adding them
to the memblock reserved list during early boot. If memory reservation
fails (e.g. a region has already been reserved), all preserved pages
are dropped.
For efficiency the preserved pages pagetable is used to identify and
reserve
Rather than adding one page at a time to the page cache and taking the
page cache xarray lock each time, where possible add pages in bulk by
first populating an xarray node outside of the page cache before taking
the lock to insert it.
When a group of pages to be inserted will fill an xarray node,
Add and remove pkram_link pages from a pkram_obj atomically to prepare
for multithreading.
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 27 ++-
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/mm/pkram.c b/mm/pkram.c
index 5f4e4d12865f..042c14dedc25 100644
Support preserving a transparent hugepage by recording the page order and
a flag indicating it is a THP. Use these values when the page is
restored to reconstruct the THP.
Signed-off-by: Anthony Yznaga
---
include/linux/pkram.h | 2 ++
mm/pkram.c| 20
2 files c
In order to facilitate fast initialization of page structs for
preserved pages, memblocks with preserved pages must not cross
numa node boundaries and must have a node id assigned to them.
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 10 ++
1 file changed, 10 insertions(+)
diff --git
To prepare for multithreading the work done to a preserve a file,
divide the work into subranges of the total index range of the file.
The chunk size is a rather arbitrary 256k indices.
A new API call, pkram_prepare_save_chunk(), is added. It is called
after calling pkram_prepare_save_obj(), and
This patch adds three functions:
pkram_prepare_load_pages()
Called after calling pkram_prepare_load_obj()
pkram_load_pages()
Loads some number of pages that are contiguous by their original
file index values. The index of the first page, an array of the
page pointers, and the number of p
Make use of new interfaces for loading and inserting preserved pages
into a shmem file in bulk.
Signed-off-by: Anthony Yznaga
---
mm/shmem_pkram.c | 23 +--
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/mm/shmem_pkram.c b/mm/shmem_pkram.c
index 4992b6c3e54e..
Preserved pages are represented in the memblock reserved list, but page
structs for pages in the reserved list are initialized early while boot
is single threaded which means that a large number of preserved pages
can impact boot time. To mitigate, defer initialization of preserved
pages by skippin
Add the ability to walk the pkram pagetable from high to low addresses
and execute a callback for each contiguous range of preserved or not
preserved memory found. The reason for walking high to low is to align
with high to low memblock allocation when finding holes that memblocks
can safely be al
To support deferred initialization of page structs for preserved
pages, add an iterator of the memblock reserved list that can select or
exclude ranges based on memblock flags.
Signed-off-by: Anthony Yznaga
---
include/linux/memblock.h | 10 ++
mm/memblock.c| 51 +
Calling shmem_insert_page() to insert one page at a time does
not scale well when multiple threads are inserting pages into
the same shmem segment. This is primarily due to the locking needed
when adding to the pagecache and LRU but also due to contention
on the shmem_inode_info lock. To address t
PKRAM nodes are further divided into a list of objects. After a save
operation has been initiated for a node, a save operation for an object
associated with the node is initiated by calling pkram_prepare_save_obj().
A new object is created and linked to the node. The save operation for
the object
Using the pkram_save_page() function, one can populate PKRAM objects with
memory pages which can later be loaded using the pkram_load_page()
function. Saving a memory page to PKRAM is accomplished by recording
its pfn and incrementing its refcount so that it will not be freed after
the last user pu
Avoid regions of memory that contain preserved pages when computing
slots used to select where to put the decompressed kernel.
Signed-off-by: Anthony Yznaga
---
arch/x86/boot/compressed/Makefile | 3 +
arch/x86/boot/compressed/kaslr.c | 67 ++
arch/x86/boot/compressed/misc.h | 19
Explicitly specify the mm to pass to shmem_insert_page() when
the pkram_stream is initialized rather than use the mm of the
current thread. This will allow for multiple kernel threads to
target the same mm when inserting pages in parallel.
Signed-off-by: Anthony Yznaga
---
include/linux/pkram.h
The function inserts a page into a shmem file at a specified offset.
The page can be a regular PAGE_SIZE page or a transparent huge page.
If there is something at the offset (page or swap), the function fails.
The function will be used by the next patch.
Originally-by: Vladimir Davydov
Signed-of
The kdump kernel should not preserve or restore pages.
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 8 ++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/pkram.c b/mm/pkram.c
index 95e691382721..4d4d836fea53 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -1,4 +1,5 @@
// SP
Ensure destination ranges of the kexec segments do not overlap
with any kernel pages marked to be preserved across kexec.
For kexec_load, return EADDRNOTAVAIL if overlap is detected.
For kexec_file_load, skip ranges containing preserved pages when
seaching for available ranges to use.
Signed-off
Preserved memory is divided into nodes which can be saved and loaded
independently of each other. PKRAM nodes are kept on a list and
identified by unique names. Whenever a save operation is initiated by
calling pkram_prepare_save(), a new node is created and linked to the
list. When the save operat
Workaround the limitation that shmem pages must be in memory in order
to be preserved by preventing them from being swapped out in the first
place. Do this by marking shmem pages associated with a PKRAM node
as unevictable.
Signed-off-by: Anthony Yznaga
---
mm/shmem.c | 2 ++
1 file changed, 2
To free all space utilized for preserved memory, one can write 0 to
/sys/kernel/pkram. This will destroy all PKRAM nodes that are not
currently being read or written.
Originally-by: Vladimir Davydov
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 39 ++-
1 fil
When loading a kernel for kexec, dynamically update the list of physical
ranges that are not to be used for storing preserved pages with the ranges
where kexec segments will be copied to on reboot. This ensures no pages
preserved after the new kernel has been loaded will reside in these ranges
on r
This patchset implements preserved-over-kexec memory storage or PKRAM as a
method for saving memory pages of the currently executing kernel so that
they may be restored after kexec into a new kernel. The patches are adapted
from an RFC patchset sent out in 2013 by Vladimir Davydov [1]. They
introdu
The size of the memblock reserved array may be increased while preserved
pages are being reserved. When this happens, preserved pages that have
not yet been reserved are at risk for being clobbered when space for a
larger array is allocated.
When called from memblock_double_array(), a wrapper aroun
This patch adds the ability to save arbitrary byte streams up to a
total length of one page to a PKRAM object using pkram_write() to be
restored later using pkram_read().
Originally-by: Vladimir Davydov
Signed-off-by: Anthony Yznaga
---
include/linux/pkram.h | 4 +++
mm/pkram.c| 84
The PKRAM super block is the starting point for restoring preserved
memory. By providing the super block to the new kernel at boot time,
preserved memory can be reserved and made available to be restored.
To point the kernel to the location of the super block, one passes
its pfn via the 'pkram' boo
Since page structs are used for linking PKRAM nodes and cleared
on boot, organize all PKRAM nodes into a list singly-linked by pfns
before reboot to facilitate the node list restore in the new kernel.
Originally-by: Vladimir Davydov
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 50
Preserved-across-kexec memory or PKRAM is a method for saving memory
pages of the currently executing kernel and restoring them after kexec
boot into a new one. This can be utilized for preserving guest VM state,
large in-memory databases, process memory, etc. across reboot. While
DRAM-as-PMEM or a
After the page ranges in the pagetable have been reserved the pagetable
is no longer needed. Rather than free it during early boot by unreserving
page-sized blocks which can be inefficient when dealing with a large number
of blocks, wait until the page structs have been initialized and free them
a
Add a pointer to the pagetable to the pkram_super_block page.
Signed-off-by: Anthony Yznaga
---
mm/pkram.c | 20 +---
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/mm/pkram.c b/mm/pkram.c
index 5a7b8f61a55d..54b2779d0813 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@
Future patches will need a way to efficiently identify physically
contiguous ranges of preserved pages regardless of their virtual
addresses as well as a way to identify ranges that do not contain
preserved pages. To facilitate this all pages to be preserved across
kexec are added to an identity ma
On 5/6/20 3:28 PM, Rafael Aquini wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 7bc83f3d9bdf..75c02c1841b2 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-para
On Wed, May 06, 2020 at 11:24:48PM +, Luis Chamberlain wrote:
> On Wed, May 06, 2020 at 06:28:15PM -0400, Rafael Aquini wrote:
> > Analogously to the introduction of panic_on_warn, this patch
> > introduces a kernel option named panic_on_taint in order to
> > provide a simple and generic way to
On Wed, May 06, 2020 at 06:28:15PM -0400, Rafael Aquini wrote:
> Analogously to the introduction of panic_on_warn, this patch
> introduces a kernel option named panic_on_taint in order to
> provide a simple and generic way to stop execution and catch
> a coredump when the kernel gets tainted by any
Analogously to the introduction of panic_on_warn, this patch
introduces a kernel option named panic_on_taint in order to
provide a simple and generic way to stop execution and catch
a coredump when the kernel gets tainted by any given taint flag.
This is useful for debugging sessions as it avoids
Hi,
I discovered a bug while preparing my next series, which also made me
realize I had never tested the extended mode feature of netconsole. :-/
The only other user of extended output is /dev/kmsg, and it is doing it
correctly.
Explanation and patch below.
On 2020-05-01, John Ogness wrote:
> d
Typo in $SUBJECT, should be "add_memory_driver_managed" ...
--
Thanks,
David / dhildenb
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Looks good to me.
Acked-by: Pankaj Gupta
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> Currently, when adding memory, we create entries in /sys/firmware/memmap/
> as "System RAM". This will lead to kexec-tools to add that memory to the
> fixed-up initial memmap for a kexec kernel (loaded via kexec_load()). The
> memory will be considered initial System RAM by the kexec'd kernel and
Hi,
On 5/6/20 6:01 PM, Will Deacon wrote:
On Wed, May 06, 2020 at 05:32:56PM +0530, Amit Kachhap wrote:
On 5/4/20 10:47 PM, Will Deacon wrote:
On Mon, Apr 27, 2020 at 11:55:01AM +0530, Amit Daniel Kachhap wrote:
diff --git a/arch/arm64/include/asm/compiler.h
b/arch/arm64/include/asm/compiler
On Wed, May 06, 2020 at 05:32:56PM +0530, Amit Kachhap wrote:
> On 5/4/20 10:47 PM, Will Deacon wrote:
> > On Mon, Apr 27, 2020 at 11:55:01AM +0530, Amit Daniel Kachhap wrote:
> > > diff --git a/arch/arm64/include/asm/compiler.h
> > > b/arch/arm64/include/asm/compiler.h
> > > index eece20d..32d590
Hi,
On 5/4/20 11:04 PM, Will Deacon wrote:
On Mon, Apr 27, 2020 at 11:55:02AM +0530, Amit Daniel Kachhap wrote:
Add documentation for KERNELPACMASK variable being added to the vmcoreinfo.
It indicates the PAC bits mask information of signed kernel pointers if
Armv8.3-A Pointer Authentication f
Hi Will,
On 5/4/20 10:47 PM, Will Deacon wrote:
On Mon, Apr 27, 2020 at 11:55:01AM +0530, Amit Daniel Kachhap wrote:
Recently arm64 linux kernel added support for Armv8.3-A Pointer
Authentication feature. If this feature is enabled in the kernel and the
hardware supports address authentication
Hello Igor,
On Wed, May 6, 2020 at 12:21 PM Igor Russkikh wrote:
>
>
>
> > #include
> > +#include
> > #include
> > #include
> > #include
> > @@ -574,13 +575,13 @@ int qede_add_tc_flower_fltr(struct qede_dev *edev,
> > __be16 proto,
> > #define RX_RING_SIZE ((u16)BIT(RX_RING_SIZE
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