[PATCH] docs: mm: fix vm overcommit documentation for OVERCOMMIT_GUESS

[PATCH] docs: mm: fix vm overcommit documentation for OVERCOMMIT_GUESS

[vbendel]

From: Vratislav Bendel <vbendel@redhat.com>

Commit 8c7829b04c52 "mm: fix false-positive OVERCOMMIT_GUESS failures"
changed the behavior of the default OVERCOMMIT_GUESS setting.
Reflect the change also in the Documentation, namely files:
    Documentation/admin-guide/sysctl/vm.rst
    Documentation/mm/overcommit-accounting.rst

Reported-by: Jozef Bacik <jobacik@redhat.com>
Signed-off-by: Vratislav Bendel <vbendel@redhat.com>
---
 Documentation/admin-guide/sysctl/vm.rst    | 4 ++--
 Documentation/mm/overcommit-accounting.rst | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index 9b833e439f09..351443427360 100644
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -742,8 +742,8 @@ overcommit_memory
 
 This value contains a flag that enables memory overcommitment.
 
-When this flag is 0, the kernel attempts to estimate the amount
-of free memory left when userspace requests more memory.
+When this flag is 0, the kernel compares the userspace memory request
+size against total memory plus swap and rejects obvious overcommits.
 
 When this flag is 1, the kernel pretends there is always enough
 memory until it actually runs out.
diff --git a/Documentation/mm/overcommit-accounting.rst b/Documentation/mm/overcommit-accounting.rst
index a4895d6fc1c2..e2263477f6d5 100644
--- a/Documentation/mm/overcommit-accounting.rst
+++ b/Documentation/mm/overcommit-accounting.rst
@@ -8,8 +8,7 @@ The Linux kernel supports the following overcommit handling modes
 	Heuristic overcommit handling. Obvious overcommits of address
 	space are refused. Used for a typical system. It ensures a
 	seriously wild allocation fails while allowing overcommit to
-	reduce swap usage.  root is allowed to allocate slightly more
-	memory in this mode. This is the default.
+	reduce swap usage. This is the default.
 
 1
 	Always overcommit. Appropriate for some scientific
-- 
2.26.3

Re: [PATCH] docs: mm: fix vm overcommit documentation for OVERCOMMIT_GUESS

[Mike Rapoport]

On Mon, Aug 29, 2022 at 02:46:38PM +0200, vbendel@redhat.com wrote:
> From: Vratislav Bendel <vbendel@redhat.com>
> 
> Commit 8c7829b04c52 "mm: fix false-positive OVERCOMMIT_GUESS failures"
> changed the behavior of the default OVERCOMMIT_GUESS setting.
> Reflect the change also in the Documentation, namely files:
>     Documentation/admin-guide/sysctl/vm.rst
>     Documentation/mm/overcommit-accounting.rst
> 
> Reported-by: Jozef Bacik <jobacik@redhat.com>
> Signed-off-by: Vratislav Bendel <vbendel@redhat.com>

Acked-by: Mike Rapoport <rppt@linux.ibm.com>

> ---
>  Documentation/admin-guide/sysctl/vm.rst    | 4 ++--
>  Documentation/mm/overcommit-accounting.rst | 3 +--
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
> index 9b833e439f09..351443427360 100644
> --- a/Documentation/admin-guide/sysctl/vm.rst
> +++ b/Documentation/admin-guide/sysctl/vm.rst
> @@ -742,8 +742,8 @@ overcommit_memory
>  
>  This value contains a flag that enables memory overcommitment.
>  
> -When this flag is 0, the kernel attempts to estimate the amount
> -of free memory left when userspace requests more memory.
> +When this flag is 0, the kernel compares the userspace memory request
> +size against total memory plus swap and rejects obvious overcommits.
>  
>  When this flag is 1, the kernel pretends there is always enough
>  memory until it actually runs out.
> diff --git a/Documentation/mm/overcommit-accounting.rst b/Documentation/mm/overcommit-accounting.rst
> index a4895d6fc1c2..e2263477f6d5 100644
> --- a/Documentation/mm/overcommit-accounting.rst
> +++ b/Documentation/mm/overcommit-accounting.rst
> @@ -8,8 +8,7 @@ The Linux kernel supports the following overcommit handling modes
>  	Heuristic overcommit handling. Obvious overcommits of address
>  	space are refused. Used for a typical system. It ensures a
>  	seriously wild allocation fails while allowing overcommit to
> -	reduce swap usage.  root is allowed to allocate slightly more
> -	memory in this mode. This is the default.
> +	reduce swap usage. This is the default.
>  
>  1
>  	Always overcommit. Appropriate for some scientific
> -- 
> 2.26.3
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH] docs: mm: fix vm overcommit documentation for OVERCOMMIT_GUESS

[Jonathan Corbet]

Vratislav Bendel <vbendel@redhat.com> writes:

> On Mon, Aug 29, 2022 at 3:45 PM Mike Rapoport <rppt@kernel.org> wrote:
>
>  On Mon, Aug 29, 2022 at 02:46:38PM +0200, vbendel@redhat.com wrote:
>  > From: Vratislav Bendel <vbendel@redhat.com>
>  > 
>  > Commit 8c7829b04c52 "mm: fix false-positive OVERCOMMIT_GUESS failures"
>  > changed the behavior of the default OVERCOMMIT_GUESS setting.
>  > Reflect the change also in the Documentation, namely files:
>  >     Documentation/admin-guide/sysctl/vm.rst
>  >     Documentation/mm/overcommit-accounting.rst
>  > 
>  > Reported-by: Jozef Bacik <jobacik@redhat.com>
>  > Signed-off-by: Vratislav Bendel <vbendel@redhat.com>
>
>  Acked-by: Mike Rapoport <rppt@linux.ibm.com>
>
> Hello,
>
> Poking this one as it's been Acked here without merging for over a
> year.  My humble opinion is that Docs should be up to date, reflecting
> the real behavior.

My humble opinion is that I must have screwed up somewhere; not sure how
this fell through the cracks.  I've applied it now, thanks and sorry for
the delay.

jon