verified the same revert is on Impish/Focal/Bionic. switching
verification completed for those

** Tags removed: verification-needed-bionic verification-needed-focal 
verification-needed-impish
** Tags added: verification-done-bionic verification-done-focal 
verification-done-impish

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https://bugs.launchpad.net/bugs/1947709

Title:
  Drop "UBUNTU: SAUCE: cachefiles: Page leaking in
  cachefiles_read_backing_file while vmscan is active"

Status in linux package in Ubuntu:
  Confirmed
Status in linux source package in Bionic:
  Fix Committed
Status in linux source package in Focal:
  Fix Committed
Status in linux source package in Hirsute:
  Fix Committed
Status in linux source package in Impish:
  Fix Committed
Status in linux source package in Jammy:
  Confirmed

Bug description:
  [Impact]

  "UBUNTU: SAUCE: cachefiles: Page leaking in
  cachefiles_read_backing_file while vmscan is active" has been applied
  to fix a page leaking issue.

  However a slightly different fix has been applied upstream:

  9a24ce5b66f9c8190d63b15f4473600db4935f1f cachefiles: Fix page leak in
  cachefiles_read_backing_file while vmscan is active

  Basically we are fixing the same issue in two different ways at the
  same time, but even worse our patch an introduce a potential NULL
  pointer dereference: we do a put_page(newpage) and set newpage = NULL
  in the main for() loop and then we may do additional put_page(newpage)
  after the main for loop if ret == -EEXIST, that would trigger the NULL
  pointer dereference.

  [Test case]

  No test case or reproducer is available at the moment, this issue has
  been found simply by reviewing the code.

  [Fix]

  Drop the SAUCE patch and rely on the upstream fix.

  [Regression potential]

  If the analysis is not correct we may re-introduce a page leak in
  cachefiles (NFS for example), but it seems unlikely to happen, since the 
upstream fix is addressing the page leaking already.

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