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[[!meta copyright="Copyright © 2012,2025 Free Software Foundation, Inc."]]
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[[!tag open_issue_gnumach]]
[[!toc]]
# Out of memory situations
GNU Mach currently does not know how much room mach-defpager has. When it is
full, mach-defpager will start not being able to write data and thus just
lose it. The corresponding object will trigger SIGBUS on access to lost data
(hopefully killing the corresponding process, thus releasing memory).
GNU Mach should be aware of how much is left, to better manage paging out,
possibly throttling some processes. Hopefully ext2fs will be able to page out
dirty data and release memory. With overcommit control we can then avoid one
process filling the whole memory+swap with anonymous data. If several processes
cooperate in sucking memory, we'd have to OOM some of them.
E.g. `vm_page_evict` would know not to try to evict an internal page, and just
wait for the external pages to get paged out and get released.
# IRC, OFTC, #debian-hurd, 2012-06-16
<lifeng> I allocated a 5GB partition as swap, but hurd only found 1GB
<youpi> use 2GiB swaps only, >2Gib are not supported
<youpi> (and apparently it just truncates the size, to be investigated)
## IRC, freenode, #hurd, 2013-10-25
<C-Keen> mkswap truncated the swap partiton to 2GB
<teythoon> :/
<teythoon> have you checked with 'free' ?
<teythoon> I have a 4gb swap partition on one of my boxes
<C-Keen> how did you create it?
<C-Keen> 2gig swap alright
<C-Keen> according to free
# Swap Files
## IRC, freenode, #hurd, 2013-10-25
<braunr> C-Keen: swapfiles are not to work very badly on the hurd
<braunr> swapfiles cause recursion and reservation problems on every system
but on the hurd, we just never took the time to fix the swap code
Same issues as we generally would have with `hurd-defpager`?
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