dd862deb15
SWAP_UNUSE_MAX_TRIES 3 appeared to work well in earlier testing, but further testing has proved it to be a source of unnecessary swapoff EBUSY failures (which can then be followed by unmount EBUSY failures). When mmget_not_zero() or shmem's igrab() fails, there is an mm exiting or inode being evicted, freeing up swap independent of try_to_unuse(). Those typically completed much sooner than the old quadratic swapoff, but now it's more common that swapoff may need to wait for them. It's possible to move those cases from init_mm.mmlist and shmem_swaplist to separate "exiting" swaplists, and try_to_unuse() then wait for those lists to be emptied; but we've not bothered with that in the past, and don't want to risk missing some other forgotten case. So just revert to cycling around until the swap is gone, without any retries limit. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1904081256170.1523@eggly.anvils Fixes: b56a2d8af914 ("mm: rid swapoff of quadratic complexity") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca> Cc: Huang Ying <ying.huang@intel.com> Cc: Kelley Nielsen <kelleynnn@gmail.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Rik van Riel <riel@surriel.com> Cc: Vineeth Pillai <vpillai@digitalocean.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.