7f6dcffb44
Introduce preempt_[dis|enable_nested() and use it to clean up various places which have open coded PREEMPT_RT conditionals. On PREEMPT_RT enabled kernels, spinlocks and rwlocks are neither disabling preemption nor interrupts. Though there are a few places which depend on the implicit preemption/interrupt disable of those locks, e.g. seqcount write sections, per CPU statistics updates etc. PREEMPT_RT added open coded CONFIG_PREEMPT_RT conditionals to disable/enable preemption in the related code parts all over the place. That's hard to read and does not really explain why this is necessary. Linus suggested to use helper functions (preempt_disable_nested() and preempt_enable_nested()) and use those in the affected places. On !RT enabled kernels these functions are NOPs, but contain a lockdep assert to validate that preemption is actually disabled to catch call sites which do not have preemption disabled. Clean up the affected code paths in mm, dentry and lib. -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmM9c8MTHHRnbHhAbGlu dXRyb25peC5kZQAKCRCmGPVMDXSYobrrEADHkvkCUHxRlarfinQY2rxEpC4nbnAg ibg+LWpDpqqZwkjADExu6+lsbb0mCdvlFyvSPwY2YcQAkj/bkTAXvdf3KjejTl++ B1J5/Cr5lyyKjajjl1efxdORgATBvwuEjR2moJiU868ZR3K4vgflN9n51A0U+NAn 3kOj/TYotFlyDNJeoK/8edqZwKaueXs3fsYGC1aq2X8mQLI4QDeaHUR6R8CU4w+X bVSIdKNluIYxyc3Eav5sDwzyF6gOSL+9DtZcVyXxJ6+PrkDdkptO23derVHk19WE ymdAwVX6S37L6HNhJgqeScs+s3xD8KDmvu5ktEAtqC0unBP8JwOFZKCZaaYj91j3 iMjMC4UFcXI5sERWhDXTSja2g0pYV6q3myfYfojxe6xXHlrVs42gCzDpOI4LZncM lvPfmhb7JR7zEmBEvVyEOX8B16ecWnUqgihU17a3ogGdKW1PRNWcWj3RmNXDmpGD YZsZSfsawMSJsDIrNRCydXrsiFBNIoVStN7K7c+blnNV8ER5rt24dqCJyUhrl4fB K8hNvDp+T8N0f6nlIUWk42vjhskEo2ijCnpvHSXQc1UL7WmLfaJf3/T9zlufPwqJ 7yVuWd9vZIb3iVAKz+LqOzLlHcgeJmYlbSBsj+Ay1UHPsNgYulDEKcuNniVoG39u zFgHu3OmIRueHA== =3M58 -----END PGP SIGNATURE----- Merge tag 'sched-rt-2022-10-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull preempt RT updates from Thomas Gleixner: "Introduce preempt_[dis|enable_nested() and use it to clean up various places which have open coded PREEMPT_RT conditionals. On PREEMPT_RT enabled kernels, spinlocks and rwlocks are neither disabling preemption nor interrupts. Though there are a few places which depend on the implicit preemption/interrupt disable of those locks, e.g. seqcount write sections, per CPU statistics updates etc. PREEMPT_RT added open coded CONFIG_PREEMPT_RT conditionals to disable/enable preemption in the related code parts all over the place. That's hard to read and does not really explain why this is necessary. Linus suggested to use helper functions (preempt_disable_nested() and preempt_enable_nested()) and use those in the affected places. On !RT enabled kernels these functions are NOPs, but contain a lockdep assert to validate that preemption is actually disabled to catch call sites which do not have preemption disabled. Clean up the affected code paths in mm, dentry and lib" * tag 'sched-rt-2022-10-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: u64_stats: Streamline the implementation flex_proportions: Disable preemption entering the write section. mm/compaction: Get rid of RT ifdeffery mm/memcontrol: Replace the PREEMPT_RT conditionals mm/debug: Provide VM_WARN_ON_IRQS_ENABLED() mm/vmstat: Use preempt_[dis|en]able_nested() dentry: Use preempt_[dis|en]able_nested() preempt: Provide preempt_[dis|en]able_nested()