dbuf: separate refcount calls for dbuf and dbuf_user #16191
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If I boot the affected system with this patch, I get the panic below. Though, this is the result of patching FreeBSD's in-tree copy of OpenZFS, which might be different enough from |
In 92dc4ad I updated the dbuf_cache accounting to track the size of userdata associated with dbufs. This adds the size of the dbuf+userdata together in a single call to zfs_refcount_add_many(), but sometime removes them in separate calls to zfs_refcount_remove_many(), if dbuf and userdata are evicted separately. What I didn't realise is that when refcount tracking is on, zfs_refcount_add_many() and zfs_refcount_remove_many() are expected to be paired, with their second & third args (count & holder) the same on both sides. Splitting the remove part into two calls means the counts don't match up, tripping a panic. This commit fixes that, by always adding and removing the dbuf and userdata counts separately. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reported-by: Mark Johnston <markj@FreeBSD.org> Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
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Ugh, that's my mistake - overexcited copypasta. Updated. Re in-tree, it'll be the same in main, but not in 14; specifically, after freebsd/freebsd-src@a2b560cc. It wouldn't apply cleanly without that, so I reckon you're good. |
The new version appears to fix the problem for me, thanks! As expected, the ARC leak is still there. |
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In 92dc4ad I updated the dbuf_cache accounting to track the size of userdata associated with dbufs. This adds the size of the dbuf+userdata together in a single call to zfs_refcount_add_many(), but sometime removes them in separate calls to zfs_refcount_remove_many(), if dbuf and userdata are evicted separately. What I didn't realise is that when refcount tracking is on, zfs_refcount_add_many() and zfs_refcount_remove_many() are expected to be paired, with their second & third args (count & holder) the same on both sides. Splitting the remove part into two calls means the counts don't match up, tripping a panic. This commit fixes that, by always adding and removing the dbuf and userdata counts separately. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reported-by: Mark Johnston <markj@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Signed-off-by: Rob Norris <rob.norris@klarasystems.com> Closes openzfs#16191
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Motivation and Context
Investigation on #15802 found this. This is probably not the fix for that, but it is in the way of hunting it down.
Description
In 92dc4ad I updated the dbuf_cache accounting to track the size of userdata associated with dbufs. This adds the size of the dbuf+userdata together in a single call to zfs_refcount_add_many(), but sometime removes them in separate calls to zfs_refcount_remove_many(), if dbuf and userdata are evicted separately.
What I didn't realise is that when refcount tracking is on, zfs_refcount_add_many() and zfs_refcount_remove_many() are expected to be paired, with their second & third args (count & holder) the same on both sides. Splitting the remove part into two calls means the counts don't match up, tripping a panic.
This commit fixes that, by always adding and removing the dbuf and userdata counts separately.
How Has This Been Tested?
Just light sanity checking Test suite run with debug enabled is in progress.
Types of changes
Checklist:
Signed-off-by.