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While at it, change VM_BUG_ON() to >> VM_WARN_ON_ONCE_PAGE(). > > Is it really safe to do that? This is based on our coding style[1], do not crash the kernel and use WARN() rather than BUG(). For these two checks, they are making sure zspage chains are formed correctly and related errors should be caught at development phase. IMHO, VM_WARN_ON_ONCE_PAGE() is sufficient. In MM, we convert BUG() to WARN() when we are touching the code. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /Documentation/process/coding-style.rst?h=3Dv7.2-rc6#n1225 --=20 Best Regards, Yan, Zi