Re: panic: kmem_malloc(131072): kmem_map too small (AMD64)

Ruslan Ermilov wrote:
On Mon, Sep 24, 2007 at 08:04:33AM -0500, Larry Rosenman wrote:
On Mon, 24 Sep 2007, Kris Kennaway wrote:

Ruslan Ermilov wrote:
On Sat, Sep 22, 2007 at 11:37:37PM +0200, Kris Kennaway wrote:
Darren Reed wrote:
[...]
Stupid question, perhaps, but is vm.kmem_size/vm.kmem_size_max limited by physical RAM?
Yes.
To be precise, it's actually limited by 2 * sizeof(physical RAM).
It's still size of a _virtual_ memory map (kmem_map), after all:
: /*
: * Limit kmem virtual size to twice the physical memory.
: * This allows for kmem map sparseness, but limits the size
: * to something sane. Be careful to not overflow the 32bit
: * ints while doing the check.
: */
: if (((vm_kmem_size / 2) / PAGE_SIZE) > cnt.v_page_count)
: vm_kmem_size = 2 * cnt.v_page_count * PAGE_SIZE;
Well OK, but that seems pretty dangerous, because it leaves open a pathway to exhaust all of physical memory and presumably panic.
is KVA pageable? Is the kmem_map dedicating non-pageable memory?

kmem_map is used to map memory for the zone allocator, including
malloc(9).

I've set my vm.kmem_max to 1G, (on a 4G amd64 box). Is that reasonable?

It just means that your kernel can "malloc" up to 1G of memory.


You're all missing the point, I hate to say. What happened is that a change was made recently to more accurately account for allocated
memory. Now people are getting kmem_map_too_small panics that weren't
getting them before. So while the accounting is now more accurate, the
outcome is actually harmful. That needs to be fixed before the release.

Scott


_______________________________________________
freebsd-current@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscribe@xxxxxxxxxxx"

Relevant Pages

  • Re: panic: kmem_malloc(131072): kmem_map too small (AMD64)
    ... by physical RAM? ... Well OK, but that seems pretty dangerous, because it leaves open a pathway to exhaust all of physical memory and presumably panic. ... What happened is that a change was made recently to more accurately account for allocated ... Now people are getting kmem_map_too_small panics that weren't ...
    (freebsd-current)
  • Re: Question for you computer geeks
    ... problems with just more physical RAM. ... No, 4GB physical memory. ... They tried multiple video cards, ... The usual problem is unstable motherboard design. ...
    (rec.photo.digital)
  • Re: Question for you computer geeks
    ... problems with just more physical RAM. ... No, 4GB physical memory. ... They tried multiple video cards, ... The usual problem is unstable motherboard design. ...
    (rec.photo.digital)
  • Re: Question for you computer geeks
    ... problems with just more physical RAM. ... No, 4GB physical memory. ... they spent. ... They tried multiple video cards, ...
    (rec.photo.digital)
  • Re: panic: kmem_malloc(131072): kmem_map too small (AMD64)
    ... Well OK, but that seems pretty dangerous, because it leaves open a pathway to exhaust all of physical memory and presumably panic. ... Now people are getting kmem_map_too_small panics that weren't ... Also unless I have missed it I am not seeing the sudden flood of panic reports that may indicate sudden breakage. ...
    (freebsd-current)